diff --git a/README.md b/README.md
index 7d3a91ff..72527f86 100644
--- a/README.md
+++ b/README.md
@@ -154,7 +154,7 @@ The game includes the mods from the default [minetest_game](https://github.com/m
   * [bright_night][] ([Unlicense][lic.unlicense]) -- version: [69b750a Git][ver.bright_night] *2018-06-03*
   * [desert_life][] ([CC BY-SA][lic.ccbysa4.0]) -- version: [188f984 Git][ver.desert_life] *2020-01-24*
   * [ethereal][] ([MIT][lic.ethereal]) -- version: [2021-07-18][ver.ethereal] ([patched][patch.ethereal])
-  * [nether][] ([ISC / CC BY / CC BY-SA / CC0][lic.nether]) -- version: [3][ver.nether] *2021-01-22* ([patched][patch.nether])
+  * [nether][] ([ISC / CC BY / CC BY-SA / CC0][lic.nether]) -- version: [3.1][ver.nether] *2021-07-31* ([patched][patch.nether])
   * [snowdrift][] ([MIT / CC BY / CC BY-SA][lic.snowdrift]) -- version: [3342939 Git][ver.snowdrift] *2020-04-24* ([patched][patch.snowdrift])
 
 
@@ -396,7 +396,7 @@ The game includes the mods from the default [minetest_game](https://github.com/m
 [myroofs]: https://forum.minetest.net/viewtopic.php?t=11416
 [mysheetmetal]: https://forum.minetest.net/viewtopic.php?t=11702
 [mywoodslopes]: https://forum.minetest.net/viewtopic.php?t=11433
-[nether]: https://forum.minetest.net/viewtopic.php?t=5790
+[nether]: https://content.minetest.net/packages/PilzAdam/nether/
 [no_fall_damage]: https://forum.minetest.net/viewtopic.php?t=25876
 [painting]: https://github.com/minetest-mods/painting
 [pbmarks]: https://github.com/AntumMT/mod-pbmarks
@@ -662,7 +662,7 @@ The game includes the mods from the default [minetest_game](https://github.com/m
 [ver.myroofs]: https://github.com/minetest-mods/myroofs/tree/fe98461
 [ver.mysheetmetal]: https://github.com/minetest-mods/mysheetmetal/tree/7c5ab71
 [ver.mywoodslopes]: https://github.com/minetest-mods/mywoodslopes/tree/3a1b531
-[ver.nether]: https://github.com/minetest-mods/nether/tree/v3
+[ver.nether]: https://github.com/minetest-mods/nether/tree/v3.1
 [ver.no_fall_damage]: https://repo.or.cz/minetest_no_fall_damage.git/shortlog/refs/tags/1.0.0
 [ver.painting]: https://github.com/minetest-mods/painting/tree/da8f4ba
 [ver.pbmarks]: https://github.com/AntumMT/mod-pbmarks/releases/tag/v1.0
diff --git a/mods/world/nether/README.md b/mods/world/nether/README.md
index 9481384e..edf300fd 100644
--- a/mods/world/nether/README.md
+++ b/mods/world/nether/README.md
@@ -74,4 +74,7 @@ SOFTWARE.
  * `nether_rack`* (files starting with "nether_rack"): Zeg9
  * `nether_tool_`* (files starting with "nether_tool_"): color adjusted versions from "[default](https://github.com/minetest/minetest_game/tree/master/mods/default)" mod, originals by BlockMen
 
-All other media: Copyright © 2013 PilzAdam, licensed under CC BY-SA 3.0 by PilzAdam.
\ No newline at end of file
+### [Unlicensed but permission for inclusion by kovaszos_uborka](https://www.planetminecraft.com/member/kovaszos_uborka/)
+ * `nether_brick_deep.png` (edited by TenPlus1)
+
+All other media: Copyright © 2013 PilzAdam, licensed under CC BY-SA 3.0 by PilzAdam.
diff --git a/mods/world/nether/crafts.lua b/mods/world/nether/crafts.lua
index f880e190..88d1d07e 100644
--- a/mods/world/nether/crafts.lua
+++ b/mods/world/nether/crafts.lua
@@ -44,6 +44,14 @@ minetest.register_craft({
 	}
 })
 
+minetest.register_craft({
+	output = "nether:brick_deep 4",
+	recipe = {
+		{"nether:rack_deep", "nether:rack_deep"},
+		{"nether:rack_deep", "nether:rack_deep"}
+	}
+})
+
 minetest.register_craft({
     output = "nether:basalt_hewn",
     type = "shapeless",
@@ -61,4 +69,4 @@ minetest.register_craft({
   }
 })
 
--- See tools.lua for tools related crafting
\ No newline at end of file
+-- See tools.lua for tools related crafting
diff --git a/mods/world/nether/depends.txt b/mods/world/nether/depends.txt
index 00f426a6..2ccaf363 100644
--- a/mods/world/nether/depends.txt
+++ b/mods/world/nether/depends.txt
@@ -6,3 +6,4 @@ fire?
 loot?
 mesecons?
 moreblocks?
+climate_api?
diff --git a/mods/world/nether/init.lua b/mods/world/nether/init.lua
index c09234e1..13fcaa64 100644
--- a/mods/world/nether/init.lua
+++ b/mods/world/nether/init.lua
@@ -42,12 +42,18 @@ end
 
 -- Global Nether namespace
 nether                = {}
+nether.mapgen         = {} -- Shared Nether mapgen namespace, for mapgen files to expose functions and constants
 nether.modname        = minetest.get_current_modname()
 nether.path           = minetest.get_modpath(nether.modname)
 nether.get_translator = S
                      -- nether.useBiomes allows other mods to know whether they can register ores etc. in the Nether.
                      -- See mapgen.lua for an explanation of why minetest.read_schematic is being checked
 nether.useBiomes      = minetest.get_mapgen_setting("mg_name") ~= "v6" and minetest.read_schematic ~= nil
+nether.fogColor = {	           -- only used if climate_api is installed
+	netherCaverns = "#1D0504", -- Distance-fog colour for classic nether
+	mantle        = "#070916", -- Distance-fog colour for the Mantle region
+	geodes        = "#300530"  -- Distance-fog colour for secondary region
+}
 
 
 -- Settings
@@ -70,6 +76,19 @@ if nether.DEPTH_FLOOR + 1000 > nether.DEPTH_CEILING then
 end
 nether.DEPTH = nether.DEPTH_CEILING -- Deprecated, use nether.DEPTH_CEILING instead.
 
+-- DEPTH_FLOOR_LAYERS gives the bottom Y of all locations that wish to be
+-- considered part of the Nether.
+-- DEPTH_FLOOR_LAYERS Allows mods to insert extra layers below the
+-- Nether, by knowing where their layer ceiling should start, and letting
+-- the layers be included in effects which only happen in the Nether.
+-- If a mod wishes to add a layer below the Nether it should read
+-- nether.DEPTH_FLOOR_LAYERS to find the bottom Y of the Nether and any
+-- other layers already under the Nether. The mod should leave a small gap
+-- between DEPTH_FLOOR_LAYERS and its ceiling (e.g. use DEPTH_FLOOR_LAYERS - 6
+-- for its ceiling Y, so there is room to shift edge-case biomes), then set
+-- nether.DEPTH_FLOOR_LAYERS to reflect the mod's floor Y value, and call
+-- shift_existing_biomes() with DEPTH_FLOOR_LAYERS as the floor_y argument.
+nether.DEPTH_FLOOR_LAYERS = nether.DEPTH_FLOOR
 
 -- A debug-print function that understands vectors etc. and does not
 -- evaluate when debugging is turned off.
@@ -149,7 +168,7 @@ This opens to a truly hellish place, though for small mercies the air there is s
 The expedition parties have found no diamonds or gold, and after an experienced search party failed to return from the trail of a missing expedition party, I must conclude this is a dangerous place.]], 10 * nether.FASTTRAVEL_FACTOR),
 
 		is_within_realm = function(pos) -- return true if pos is inside the Nether
-			return pos.y < nether.DEPTH_CEILING
+			return pos.y < nether.DEPTH_CEILING and pos.y > nether.DEPTH_FLOOR
 		end,
 
 		find_realm_anchorPos = function(surface_anchorPos, player_name)
@@ -157,7 +176,7 @@ The expedition parties have found no diamonds or gold, and after an experienced
 			local destination_pos = vector.divide(surface_anchorPos, nether.FASTTRAVEL_FACTOR)
 			destination_pos.x = math.floor(0.5 + destination_pos.x) -- round to int
 			destination_pos.z = math.floor(0.5 + destination_pos.z) -- round to int
-			destination_pos.y = nether.DEPTH_CEILING - 1000 -- temp value so find_nearest_working_portal() returns nether portals
+			destination_pos.y = nether.DEPTH_CEILING - 1 -- temp value so find_nearest_working_portal() returns nether portals
 
 			-- a y_factor of 0 makes the search ignore the altitude of the portals (as long as they are in the Nether)
 			local existing_portal_location, existing_portal_orientation =
@@ -182,7 +201,7 @@ The expedition parties have found no diamonds or gold, and after an experienced
 			local destination_pos = vector.multiply(realm_anchorPos, nether.FASTTRAVEL_FACTOR)
 			destination_pos.x = math.min(30900, math.max(-30900, destination_pos.x)) -- clip to world boundary
 			destination_pos.z = math.min(30900, math.max(-30900, destination_pos.z)) -- clip to world boundary
-			destination_pos.y = 0 -- temp value so find_nearest_working_portal() doesn't return nether portals
+			destination_pos.y = nether.DEPTH_CEILING + 1 -- temp value so find_nearest_working_portal() doesn't return nether portals
 
 			-- a y_factor of 0 makes the search ignore the altitude of the portals (as long as they are outside the Nether)
 			local existing_portal_location, existing_portal_orientation =
@@ -227,7 +246,91 @@ The expedition parties have found no diamonds or gold, and after an experienced
 		end
 
 	})
-end
+
+
+	-- Set appropriate nether distance-fog if climate_api is available
+	--
+	-- Delegating to a mod like climate_api means nether won't unexpectedly stomp on the sky of
+	-- any other mod.
+	-- Skylayer is another mod which can perform this role, and skylayer support could be added
+	-- here as well. However skylayer doesn't provide a position-based method of specifying sky
+	-- colours out-of-the-box, so the nether mod will have to monitor when players enter and
+	-- leave the nether.
+	if minetest.get_modpath("climate_api") and minetest.global_exists("climate_api") and climate_api.register_weather ~= nil then
+
+		climate_api.register_influence(
+			"nether_biome",
+			function(pos)
+				local result = "surface"
+
+				if pos.y <= nether.DEPTH_CEILING and pos.y >= nether.DEPTH_FLOOR then
+					result = "nether"
+
+					-- since mapgen_nobiomes.lua has no regions it doesn't implement get_region(),
+					-- so only use get_region() if it exists
+					if nether.mapgen.get_region ~= nil then
+						-- the biomes-based mapgen supports 2 extra regions
+						local regions = nether.mapgen.RegionEnum
+						local region  = nether.mapgen.get_region(pos)
+						if region == regions.CENTER or region == regions.CENTERSHELL then
+							result = "mantle"
+						elseif region == regions.NEGATIVE or region == regions.NEGATIVESHELL then
+							result = "geode"
+						end
+					end
+				end
+
+				return result
+			end
+		)
+
+		-- using sky type "plain" unfortunately means we don't get smooth fading transitions when
+		-- the color of the sky changes, but it seems to be the only way to obtain a sky colour
+		-- which doesn't brighten during the daytime.
+		local undergroundSky = {
+			sky_data = {
+				base_color = nil,
+				type = "plain",
+				textures = nil,
+				clouds = false,
+			},
+			sun_data = {
+				visible = false,
+				sunrise_visible = false
+			},
+			moon_data = {
+				visible = false
+			},
+			star_data = {
+				visible = false
+			}
+		}
+
+		local netherSky, mantleSky, geodeSky = table.copy(undergroundSky), table.copy(undergroundSky), table.copy(undergroundSky)
+		netherSky.sky_data.base_color = nether.fogColor.netherCaverns
+		mantleSky.sky_data.base_color = nether.fogColor.mantle
+		geodeSky.sky_data.base_color  = nether.fogColor.geodes
+
+		climate_api.register_weather(
+			"nether:nether",
+			{ nether_biome = "nether" },
+			{ ["climate_api:skybox"] = netherSky }
+		)
+
+		climate_api.register_weather(
+			"nether:mantle",
+			{ nether_biome = "mantle" },
+			{ ["climate_api:skybox"] = mantleSky }
+		)
+
+		climate_api.register_weather(
+			"nether:geode",
+			{ nether_biome = "geode" },
+			{ ["climate_api:skybox"] = geodeSky }
+		)
+	end
+
+end -- end of "if nether.NETHER_REALM_ENABLED..."
 
 
 -- Play bubbling lava sounds if player killed by lava
diff --git a/mods/world/nether/locale/nether.fr.tr b/mods/world/nether/locale/nether.fr.tr
index 48201d8c..f274f9b2 100644
--- a/mods/world/nether/locale/nether.fr.tr
+++ b/mods/world/nether/locale/nether.fr.tr
@@ -13,9 +13,25 @@ Construction requires 14 blocks of obsidian, which we found deep underground whe
 
 Nether Portal=Portail du Nether
 
+### mapgen_mantle.lua ###
+
+, @1m above lava-sea level=
+, @1m below lava-sea level=
+, approaching y boundary of Nether=
+@1@2@3@4=
+Center/Mantle, but outside the caverns=
+Center/Mantle, inside cavern=
+Describes which region of the nether the player is in=
+Negative nether=
+Positive nether=
+Shell between negative nether and center region=
+Shell between positive nether and center region=
+The Overworld=
+Unknown player position=
+[Perlin @1] =
+
 ### nodes.lua ###
 
-=
 A finely finished block of solid Nether Basalt.=
 A rough cut solid block of Nether Basalt.=
 A thin crust of cooled lava with liquid lava beneath=
diff --git a/mods/world/nether/locale/template.txt b/mods/world/nether/locale/template.txt
index 0dfcf324..ef69c76e 100644
--- a/mods/world/nether/locale/template.txt
+++ b/mods/world/nether/locale/template.txt
@@ -12,9 +12,25 @@ Construction requires 14 blocks of obsidian, which we found deep underground whe
 
 Nether Portal=
 
+### mapgen_mantle.lua ###
+
+, @1m above lava-sea level=
+, @1m below lava-sea level=
+, approaching y boundary of Nether=
+@1@2@3@4=
+Center/Mantle, but outside the caverns=
+Center/Mantle, inside cavern=
+Describes which region of the nether the player is in=
+Negative nether=
+Positive nether=
+Shell between negative nether and center region=
+Shell between positive nether and center region=
+The Overworld=
+Unknown player position=
+[Perlin @1] =
+
 ### nodes.lua ###
 
-=
 A finely finished block of solid Nether Basalt.=
 A rough cut solid block of Nether Basalt.=
 A thin crust of cooled lava with liquid lava beneath=
diff --git a/mods/world/nether/mapgen.lua b/mods/world/nether/mapgen.lua
index c82a7dbf..df82e584 100644
--- a/mods/world/nether/mapgen.lua
+++ b/mods/world/nether/mapgen.lua
@@ -45,7 +45,6 @@ local BASALT_COLUMN_LOWER_LIMIT = CENTER_CAVERN_LIMIT * 0.25      -- This value
 
 -- Shared Nether mapgen namespace
 -- For mapgen files to share functions and constants
-nether.mapgen = {}
 local mapgen = nether.mapgen
 
 mapgen.TCAVE                     = TCAVE                     -- const needed in mapgen_mantle.lua
@@ -69,7 +68,8 @@ if minetest.read_schematic == nil then
 	error("This " .. nether.modname .. " mapgen requires Minetest v5.1 or greater, use mapgen_nobiomes.lua instead.", 0)
 end
 
--- Load helper functions for generating the mantle / center region
+-- Load specialty helper functions
+dofile(nether.path .. "/mapgen_dungeons.lua")
 dofile(nether.path .. "/mapgen_mantle.lua")
 
 
@@ -81,7 +81,8 @@ local math_max, math_min, math_abs, math_floor = math.max, math.min, math.abs, m
 
 -- Inject nether_caverns biome
 
-local function override_underground_biomes()
+-- Move any existing biomes out of the y-range specified by 'floor_y' and 'ceiling_y'
+mapgen.shift_existing_biomes = function(floor_y, ceiling_y)
 	-- https://forum.minetest.net/viewtopic.php?p=257522#p257522
 	-- Q: Is there a way to override an already-registered biome so I can get it out of the
 	--    way of my own underground biomes without disturbing the other biomes registered by
@@ -108,7 +109,7 @@ local function override_underground_biomes()
 	end
 	for old_ore_key, old_ore_def in pairs(minetest.registered_ores) do
 		registered_ores_copy[old_ore_key] = old_ore_def
-	 end
+	end
 
 	-- clear biomes, decorations, and ores
 	minetest.clear_registered_decorations()
@@ -117,23 +118,36 @@ local function override_underground_biomes()
 
 	-- Restore biomes, adjusted to not overlap the Nether
 	for biome_key, new_biome_def in pairs(registered_biomes_copy) do
-		local biome_y_max, biome_y_min = tonumber(new_biome_def.y_max), tonumber(new_biome_def.y_min)
+		-- follow similar min_pos/max_pos processing logic as read_biome_def() in l_mapgen.cpp
+		local biome_y_max, biome_y_min = 31000, -31000
+		if type(new_biome_def.min_pos) == 'table' and type(new_biome_def.min_pos.y) == 'number' then biome_y_min = new_biome_def.min_pos.y end
+		if type(new_biome_def.max_pos) == 'table' and type(new_biome_def.max_pos.y) == 'number' then biome_y_max = new_biome_def.max_pos.y end
+		if type(new_biome_def.y_min) == 'number' then biome_y_min = new_biome_def.y_min end
+		if type(new_biome_def.y_max) == 'number' then biome_y_max = new_biome_def.y_max end
 
-		if biome_y_max > NETHER_FLOOR and biome_y_min < NETHER_CEILING then
+		if biome_y_max > floor_y and biome_y_min < ceiling_y then
 			-- This biome occupies some or all of the depth of the Nether, shift/crop it.
-			local spaceOccupiedAbove = biome_y_max - NETHER_CEILING
-			local spaceOccupiedBelow = NETHER_FLOOR - biome_y_min
+			local new_y_min, new_y_max
+			local spaceOccupiedAbove = biome_y_max - ceiling_y
+			local spaceOccupiedBelow = floor_y - biome_y_min
 			if spaceOccupiedAbove >= spaceOccupiedBelow or biome_y_min <= -30000 then
 				-- place the biome above the Nether
 				-- We also shift biomes which extend to the bottom of the map above the Nether, since they
 				-- likely only extend that deep as a catch-all, and probably have a role nearer the surface.
-				new_biome_def.y_min = NETHER_CEILING + 1
-				new_biome_def.y_max = math_max(biome_y_max, NETHER_CEILING + 2)
+				new_y_min = ceiling_y + 1
+				new_y_max = math_max(biome_y_max, ceiling_y + 2)
 			else
 				-- shift the biome to below the Nether
-				new_biome_def.y_max = NETHER_FLOOR - 1
-				new_biome_def.y_min = math_min(biome_y_min, NETHER_CEILING - 2)
+				new_y_max = floor_y - 1
+				new_y_min = math_min(biome_y_min, floor_y - 2)
 			end
+
+			debugf("Moving biome \"%s\" from %s..%s to %s..%s", new_biome_def.name, new_biome_def.y_min, new_biome_def.y_max, new_y_min, new_y_max)
+
+			if type(new_biome_def.min_pos) == 'table' and type(new_biome_def.min_pos.y) == 'number' then new_biome_def.min_pos.y = new_y_min end
+			if type(new_biome_def.max_pos) == 'table' and type(new_biome_def.max_pos.y) == 'number' then new_biome_def.max_pos.y = new_y_max end
+			new_biome_def.y_min = new_y_min -- Ensure the new heights are saved, even if original biome never specified one
+			new_biome_def.y_max = new_y_max
 		end
 		minetest.register_biome(new_biome_def)
 	end
@@ -149,7 +163,7 @@ local function override_underground_biomes()
  end
 
 -- Shift any overlapping biomes out of the way before we create the Nether biomes
-override_underground_biomes()
+mapgen.shift_existing_biomes(NETHER_FLOOR, NETHER_CEILING)
 
 -- nether:native_mapgen is used to prevent ores and decorations being generated according
 -- to landforms created by the native mapgen.
@@ -244,6 +258,19 @@ mapgen.np_cave = {
 	--flags = ""
 }
 
+local cavePointPerlin = nil
+
+mapgen.get_cave_point_perlin = function()
+	cavePointPerlin = cavePointPerlin or minetest.get_perlin(mapgen.np_cave)
+	return cavePointPerlin
+end
+
+mapgen.get_cave_perlin_at = function(pos)
+	cavePointPerlin = cavePointPerlin or minetest.get_perlin(mapgen.np_cave)
+	return cavePointPerlin:get_3d(pos)
+end
+
+
 -- Buffers and objects we shouldn't recreate every on_generate
 
 local nobj_cave = nil
@@ -256,206 +283,11 @@ local dbuf = {}
 local c_air              = minetest.get_content_id("air")
 local c_netherrack       = minetest.get_content_id("nether:rack")
 local c_netherrack_deep  = minetest.get_content_id("nether:rack_deep")
-local c_dungeonbrick     = minetest.get_content_id("nether:brick")
-local c_dungeonbrick_alt = minetest.get_content_id("nether:brick_cracked")
-local c_netherbrick_slab = minetest.get_content_id("stairs:slab_nether_brick")
-local c_netherfence      = minetest.get_content_id("nether:fence_nether_brick")
-local c_glowstone        = minetest.get_content_id("nether:glowstone")
-local c_lava_source      = minetest.get_content_id("default:lava_source")
 local c_lavasea_source   = minetest.get_content_id("nether:lava_source") -- same as lava but with staggered animation to look better as an ocean
 local c_lava_crust       = minetest.get_content_id("nether:lava_crust")
 local c_native_mapgen    = minetest.get_content_id("nether:native_mapgen")
 
 
--- Dungeon excavation functions
-
-function is_dungeon_brick(node_id)
-	return node_id == c_dungeonbrick or node_id == c_dungeonbrick_alt
-end
-
-function build_dungeon_room_list(data, area)
-
-	local result = {}
-
-	-- Unfortunately gennotify only returns dungeon rooms, not corridors.
-	-- We don't need to check for temples because only dungeons are generated in biomes
-	-- that define their own dungeon nodes.
-	local gennotify = minetest.get_mapgen_object("gennotify")
-	local roomLocations = gennotify["dungeon"] or {}
-
-	-- Excavation should still know to stop if a cave or corridor has removed the dungeon wall.
-	-- See MapgenBasic::generateDungeons in mapgen.cpp for max room sizes.
-	local maxRoomSize = 18
-	local maxRoomRadius = math.ceil(maxRoomSize / 2)
-
-	local xStride, yStride, zStride = 1, area.ystride, area.zstride
-	local minEdge, maxEdge = area.MinEdge, area.MaxEdge
-
-	for _, roomPos in ipairs(roomLocations) do
-
-		if area:containsp(roomPos) then -- this safety check does not appear to be necessary, but lets make it explicit
-
-			local room_vi = area:indexp(roomPos)
-			--data[room_vi] = minetest.get_content_id("default:torch") -- debug
-
-			local startPos = vector.new(roomPos)
-			if roomPos.y + 1 <= maxEdge.y and data[room_vi + yStride] == c_air then
-				-- The roomPos coords given by gennotify are at floor level, but whenever possible we
-				-- want to be performing searches a node higher than floor level to avoids dungeon chests.
-				startPos.y = startPos.y + 1
-				room_vi = area:indexp(startPos)
-			end
-
-			local bound_min_x = math_max(minEdge.x, roomPos.x - maxRoomRadius)
-			local bound_min_y = math_max(minEdge.y, roomPos.y - 1) -- room coords given by gennotify are on the floor
-			local bound_min_z = math_max(minEdge.z, roomPos.z - maxRoomRadius)
-
-			local bound_max_x = math_min(maxEdge.x, roomPos.x + maxRoomRadius)
-			local bound_max_y = math_min(maxEdge.y, roomPos.y + maxRoomSize) -- room coords given by gennotify are on the floor
-			local bound_max_z = math_min(maxEdge.z, roomPos.z + maxRoomRadius)
-
-			local room_min = vector.new(startPos)
-			local room_max = vector.new(startPos)
-
-			local vi = room_vi
-			while room_max.y < bound_max_y and data[vi + yStride] == c_air do
-				room_max.y = room_max.y + 1
-				vi = vi + yStride
-			end
-
-			vi = room_vi
-			while room_min.y > bound_min_y and data[vi - yStride] == c_air do
-				room_min.y = room_min.y - 1
-				vi = vi - yStride
-			end
-
-			vi = room_vi
-			while room_max.z < bound_max_z and data[vi + zStride] == c_air do
-				room_max.z = room_max.z + 1
-				vi = vi + zStride
-			end
-
-			vi = room_vi
-			while room_min.z > bound_min_z and data[vi - zStride] == c_air do
-				room_min.z = room_min.z - 1
-				vi = vi - zStride
-			end
-
-			vi = room_vi
-			while room_max.x < bound_max_x and data[vi + xStride] == c_air do
-				room_max.x = room_max.x + 1
-				vi = vi + xStride
-			end
-
-			vi = room_vi
-			while room_min.x > bound_min_x and data[vi - xStride] == c_air do
-				room_min.x = room_min.x - 1
-				vi = vi - xStride
-			end
-
-			local roomInfo = vector.new(roomPos)
-			roomInfo.minp = room_min
-			roomInfo.maxp = room_max
-			result[#result + 1] = roomInfo
-		end
-	end
-
-	return result;
-end
-
--- Only partially excavates dungeons, the rest is left as an exercise for the player ;)
--- (Corridors and the parts of rooms which extend beyond the emerge boundary will remain filled)
-function excavate_dungeons(data, area, rooms)
-
-	local vi, node_id
-
-	-- any air from the native mapgen has been replaced by netherrack, but
-	-- we don't want this inside dungeons, so fill dungeon rooms with air
-	for _, roomInfo in ipairs(rooms) do
-
-		local room_min = roomInfo.minp
-		local room_max = roomInfo.maxp
-
-		for z = room_min.z, room_max.z do
-			for y = room_min.y, room_max.y do
-				vi = area:index(room_min.x, y, z)
-				for x = room_min.x, room_max.x do
-					node_id = data[vi]
-					if node_id == c_netherrack or node_id == c_netherrack_deep then data[vi] = c_air end
-					vi = vi + 1
-				end
-			end
-		end
-	end
-end
-
--- Since we already know where all the rooms and their walls are, and have all the nodes stored
--- in a voxelmanip already, we may as well add a little Nether flair to the dungeons found here.
-function decorate_dungeons(data, area, rooms)
-
-	local xStride, yStride, zStride = 1, area.ystride, area.zstride
-	local minEdge, maxEdge = area.MinEdge, area.MaxEdge
-
-	for _, roomInfo in ipairs(rooms) do
-
-		local room_min, room_max = roomInfo.minp, roomInfo.maxp
-		local room_size = vector.distance(room_min, room_max)
-
-		if room_size > 10 then
-			local room_seed = roomInfo.x + 3 * roomInfo.z + 13 * roomInfo.y
-			local window_y  = roomInfo.y + math_min(2, room_max.y - roomInfo.y - 1)
-
-			if room_seed % 3 == 0 and room_max.y < maxEdge.y then
-				-- Glowstone chandelier (feel free to replace with a fancy schematic)
-				local vi = area:index(roomInfo.x, room_max.y + 1, roomInfo.z)
-				if is_dungeon_brick(data[vi]) then data[vi] = c_glowstone end
-
-			elseif room_seed % 4 == 0 and room_min.y > minEdge.y
-				   and room_min.x > minEdge.x and room_max.x < maxEdge.x
-				   and room_min.z > minEdge.z and room_max.z < maxEdge.z then
-				-- lava well (feel free to replace with a fancy schematic)
-				local vi = area:index(roomInfo.x, room_min.y, roomInfo.z)
-				if is_dungeon_brick(data[vi - yStride]) then
-					data[vi - yStride] = c_lava_source
-					if data[vi - zStride] == c_air then data[vi - zStride] = c_netherbrick_slab end
-					if data[vi + zStride] == c_air then data[vi + zStride] = c_netherbrick_slab end
-					if data[vi - xStride] == c_air then data[vi - xStride] = c_netherbrick_slab end
-					if data[vi + xStride] == c_air then data[vi + xStride] = c_netherbrick_slab end
-				end
-			end
-
-			-- Barred windows
-			if room_seed % 7 < 5 and room_max.x - room_min.x >= 4 and room_max.z - room_min.z >= 4
-			   and window_y >= minEdge.y and window_y + 1 <= maxEdge.y
-			   and room_min.x > minEdge.x and room_max.x < maxEdge.x
-			   and room_min.z > minEdge.z and room_max.z < maxEdge.z then
-				--data[area:indexp(roomInfo)] = minetest.get_content_id("default:mese_post_light") -- debug
-
-				-- Until whisper glass is added, every window will be made of netherbrick fence (rather
-				-- than material depending on room_seed)
-				local window_node = c_netherfence
-
-				local vi_min = area:index(room_min.x - 1, window_y, roomInfo.z)
-				local vi_max = area:index(room_max.x + 1, window_y, roomInfo.z)
-				local locations = {-zStride, zStride, -zStride + yStride, zStride + yStride}
-				for _, offset in ipairs(locations) do
-					if is_dungeon_brick(data[vi_min + offset]) then data[vi_min + offset] = window_node end
-					if is_dungeon_brick(data[vi_max + offset]) then data[vi_max + offset] = window_node end
-				end
-				vi_min = area:index(roomInfo.x, window_y, room_min.z - 1)
-				vi_max = area:index(roomInfo.x, window_y, room_max.z + 1)
-				locations = {-xStride, xStride, -xStride + yStride, xStride + yStride}
-				for _, offset in ipairs(locations) do
-					if is_dungeon_brick(data[vi_min + offset]) then data[vi_min + offset] = window_node end
-					if is_dungeon_brick(data[vi_max + offset]) then data[vi_max + offset] = window_node end
-				end
-			end
-
-			-- Weeds on the floor once Nether weeds are added
-		end
-	end
-end
-
 
 local yblmin = NETHER_FLOOR   + BLEND * 2
 local yblmax = NETHER_CEILING - BLEND * 2
@@ -514,27 +346,29 @@ local function on_generated(minp, maxp, seed)
 	nobj_cave = nobj_cave or minetest.get_perlin_map(mapgen.np_cave, chulens)
 	local nvals_cave = nobj_cave:get_3d_map_flat(minp, nbuf_cave)
 
-	local dungeonRooms = build_dungeon_room_list(data, area)
+	local dungeonRooms = mapgen.build_dungeon_room_list(data, area) -- function from mapgen_dungeons.lua
 	local abs_cave_noise, abs_cave_noise_adjusted
 
 	local contains_nether = false
-	local contains_shell  = false
 	local contains_mantle = false
-	local contains_ocean = false
+	local contains_ocean  = false
 
 
 	for y = y0, y1 do -- Y loop first to minimise tcave & lava-sea calculations
 
-		local sea_level, cavern_limit_distance = mapgen.find_nearest_lava_sealevel(y) -- function provided by mapgen_mantle.lua
+		local sea_level, cavern_limit_distance = mapgen.find_nearest_lava_sealevel(y) -- function from mapgen_mantle.lua
 		local above_lavasea = y > sea_level
 		local below_lavasea = y < sea_level
 
 		local tcave_adj, centerRegionLimit_adj = mapgen.get_mapgenblend_adjustments(y)
 		local tcave   = TCAVE + tcave_adj
 		local tmantle = CENTER_REGION_LIMIT + centerRegionLimit_adj -- cavern_noise_adj already contains central_region_limit_adj, so tmantle is only for comparisons when cavern_noise_adj hasn't been added to the noise value
+
+		 -- cavern_noise_adj gets added to noise value instead of added to the limit np_noise
+		 -- is compared against, so subtract centerRegionLimit_adj instead of adding
 		local cavern_noise_adj =
 			CENTER_REGION_LIMIT * (cavern_limit_distance * cavern_limit_distance * cavern_limit_distance) -
-			centerRegionLimit_adj -- cavern_noise_adj gets added to noise value instead of added to the limit np_noise is compared against, so subtract centerRegionLimit_adj instead of adding
+			centerRegionLimit_adj
 
 		for z = z0, z1 do
 			local vi = area:index(x0, y, z) -- Initial voxelmanip index
@@ -581,7 +415,6 @@ local function on_generated(minp, maxp, seed)
 							else
 								-- the shell seperating the mantle from the rest of the nether...
 								data[vi] = c_netherrack -- excavate_dungeons() will mostly reverse this inside dungeons
-								contains_shell = true
 							end
 						end
 
@@ -605,12 +438,12 @@ local function on_generated(minp, maxp, seed)
 	end
 
 	if contains_mantle or contains_ocean then
-		mapgen.add_basalt_columns(data, area, minp, maxp) -- function provided by mapgen_mantle.lua
+		mapgen.add_basalt_columns(data, area, minp, maxp) -- function from mapgen_mantle.lua
 	end
 
 	if contains_nether and contains_mantle then
 		tunnelCandidate_count = tunnelCandidate_count + 1
-		local success = mapgen.excavate_tunnel_to_center_of_the_nether(data, area, nvals_cave, minp, maxp) -- function provided by mapgen_mantle.lua
+		local success = mapgen.excavate_tunnel_to_center_of_the_nether(data, area, nvals_cave, minp, maxp) -- function from mapgen_mantle.lua
 		if success then tunnel_count = tunnel_count + 1 end
 	end
 	total_chunk_count = total_chunk_count + 1
@@ -627,8 +460,8 @@ local function on_generated(minp, maxp, seed)
 
 	-- any air from the native mapgen has been replaced by netherrack, but we
 	-- don't want netherrack inside dungeons, so fill known dungeon rooms with air.
-	excavate_dungeons(data, area, dungeonRooms)
-	decorate_dungeons(data, area, dungeonRooms)
+	mapgen.excavate_dungeons(data, area, dungeonRooms) -- function from mapgen_dungeons.lua
+	mapgen.decorate_dungeons(data, area, dungeonRooms) -- function from mapgen_dungeons.lua
 
 	vm:set_data(data)
 
@@ -645,7 +478,7 @@ end
 -- use knowledge of the nether mapgen algorithm to return a suitable ground level for placing a portal.
 -- player_name is optional, allowing a player to spawn a remote portal in their own protected areas.
 function nether.find_nether_ground_y(target_x, target_z, start_y, player_name)
-	local nobj_cave_point = minetest.get_perlin(mapgen.np_cave)
+	local nobj_cave_point = mapgen.get_cave_point_perlin()
 	local air = 0 -- Consecutive air nodes found
 
 	local minp_schem, maxp_schem = nether.get_schematic_volume({x = target_x, y = 0, z = target_z}, nil, "nether_portal")
@@ -653,7 +486,7 @@ function nether.find_nether_ground_y(target_x, target_z, start_y, player_name)
 	local maxp = {x = maxp_schem.x, y = 0, z = maxp_schem.z}
 
 	for y = start_y, math_max(NETHER_FLOOR + BLEND, start_y - 4096), -1 do
-		local nval_cave = nobj_cave_point:get3d({x = target_x, y = y, z = target_z})
+		local nval_cave = nobj_cave_point:get_3d({x = target_x, y = y, z = target_z})
 
 		if nval_cave > TCAVE then -- Cavern
 			air = air + 1
@@ -677,8 +510,4 @@ function nether.find_nether_ground_y(target_x, target_z, start_y, player_name)
 	return math_max(start_y, NETHER_FLOOR + BLEND) -- Fallback
 end
 
--- We don't need to be gen-notified of temples because only dungeons will be generated
--- if a biome defines the dungeon nodes
-minetest.set_gen_notify({dungeon = true})
-
-minetest.register_on_generated(on_generated)
\ No newline at end of file
+minetest.register_on_generated(on_generated)
diff --git a/mods/world/nether/mapgen_dungeons.lua b/mods/world/nether/mapgen_dungeons.lua
new file mode 100644
index 00000000..64a73af9
--- /dev/null
+++ b/mods/world/nether/mapgen_dungeons.lua
@@ -0,0 +1,333 @@
+--[[
+
+  Nether mod for minetest
+
+  All the Dungeon related functions used by the biomes-based mapgen are here.
+
+
+  Copyright (C) 2021 Treer
+
+  Permission to use, copy, modify, and/or distribute this software for
+  any purpose with or without fee is hereby granted, provided that the
+  above copyright notice and this permission notice appear in all copies.
+
+  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
+  WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
+  WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR
+  BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES
+  OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
+  WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
+  ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
+  SOFTWARE.
+
+]]--
+
+
+-- We don't need to be gen-notified of temples because only dungeons will be generated
+-- if a biome defines the dungeon nodes
+minetest.set_gen_notify({dungeon = true})
+
+
+-- Content ids
+
+local c_air              = minetest.get_content_id("air")
+local c_netherrack       = minetest.get_content_id("nether:rack")
+local c_netherrack_deep  = minetest.get_content_id("nether:rack_deep")
+local c_dungeonbrick     = minetest.get_content_id("nether:brick")
+local c_dungeonbrick_alt = minetest.get_content_id("nether:brick_cracked")
+local c_netherbrick_slab = minetest.get_content_id("stairs:slab_nether_brick")
+local c_netherfence      = minetest.get_content_id("nether:fence_nether_brick")
+local c_glowstone        = minetest.get_content_id("nether:glowstone")
+local c_glowstone_deep   = minetest.get_content_id("nether:glowstone_deep")
+local c_lava_source      = minetest.get_content_id("default:lava_source")
+
+
+-- Misc math functions
+
+-- avoid needing table lookups each time a common math function is invoked
+local math_max, math_min  = math.max, math.min
+
+
+-- Dungeon excavation functions
+
+function is_dungeon_brick(node_id)
+	return node_id == c_dungeonbrick or node_id == c_dungeonbrick_alt
+end
+
+
+
+nether.mapgen.build_dungeon_room_list = function(data, area)
+
+	local result = {}
+
+	-- Unfortunately gennotify only returns dungeon rooms, not corridors.
+	-- We don't need to check for temples because only dungeons are generated in biomes
+	-- that define their own dungeon nodes.
+	local gennotify = minetest.get_mapgen_object("gennotify")
+	local roomLocations = gennotify["dungeon"] or {}
+
+	-- Excavation should still know to stop if a cave or corridor has removed the dungeon wall.
+	-- See MapgenBasic::generateDungeons in mapgen.cpp for max room sizes.
+	local maxRoomSize = 18
+	local maxRoomRadius = math.ceil(maxRoomSize / 2)
+
+	local xStride, yStride, zStride = 1, area.ystride, area.zstride
+	local minEdge, maxEdge = area.MinEdge, area.MaxEdge
+
+	for _, roomPos in ipairs(roomLocations) do
+
+		if area:containsp(roomPos) then -- this safety check does not appear to be necessary, but lets make it explicit
+
+			local room_vi = area:indexp(roomPos)
+			--data[room_vi] = minetest.get_content_id("default:torch") -- debug
+
+			local startPos = vector.new(roomPos)
+			if roomPos.y + 1 <= maxEdge.y and data[room_vi + yStride] == c_air then
+				-- The roomPos coords given by gennotify are at floor level, but whenever possible we
+				-- want to be performing searches a node higher than floor level to avoids dungeon chests.
+				startPos.y = startPos.y + 1
+				room_vi = area:indexp(startPos)
+			end
+
+			local bound_min_x = math_max(minEdge.x, roomPos.x - maxRoomRadius)
+			local bound_min_y = math_max(minEdge.y, roomPos.y - 1) -- room coords given by gennotify are on the floor
+			local bound_min_z = math_max(minEdge.z, roomPos.z - maxRoomRadius)
+
+			local bound_max_x = math_min(maxEdge.x, roomPos.x + maxRoomRadius)
+			local bound_max_y = math_min(maxEdge.y, roomPos.y + maxRoomSize) -- room coords given by gennotify are on the floor
+			local bound_max_z = math_min(maxEdge.z, roomPos.z + maxRoomRadius)
+
+			local room_min = vector.new(startPos)
+			local room_max = vector.new(startPos)
+
+			local vi = room_vi
+			while room_max.y < bound_max_y and data[vi + yStride] == c_air do
+				room_max.y = room_max.y + 1
+				vi = vi + yStride
+			end
+
+			vi = room_vi
+			while room_min.y > bound_min_y and data[vi - yStride] == c_air do
+				room_min.y = room_min.y - 1
+				vi = vi - yStride
+			end
+
+			vi = room_vi
+			while room_max.z < bound_max_z and data[vi + zStride] == c_air do
+				room_max.z = room_max.z + 1
+				vi = vi + zStride
+			end
+
+			vi = room_vi
+			while room_min.z > bound_min_z and data[vi - zStride] == c_air do
+				room_min.z = room_min.z - 1
+				vi = vi - zStride
+			end
+
+			vi = room_vi
+			while room_max.x < bound_max_x and data[vi + xStride] == c_air do
+				room_max.x = room_max.x + 1
+				vi = vi + xStride
+			end
+
+			vi = room_vi
+			while room_min.x > bound_min_x and data[vi - xStride] == c_air do
+				room_min.x = room_min.x - 1
+				vi = vi - xStride
+			end
+
+			local roomInfo = vector.new(roomPos)
+			roomInfo.minp = room_min
+			roomInfo.maxp = room_max
+			result[#result + 1] = roomInfo
+		end
+	end
+
+	return result;
+end
+
+-- Only partially excavates dungeons, the rest is left as an exercise for the player ;)
+-- (Corridors and the parts of rooms which extend beyond the emerge boundary will remain filled)
+nether.mapgen.excavate_dungeons = function(data, area, rooms)
+
+	local vi, node_id
+
+	-- any air from the native mapgen has been replaced by netherrack, but
+	-- we don't want this inside dungeons, so fill dungeon rooms with air
+	for _, roomInfo in ipairs(rooms) do
+
+		local room_min = roomInfo.minp
+		local room_max = roomInfo.maxp
+
+		for z = room_min.z, room_max.z do
+			for y = room_min.y, room_max.y do
+				vi = area:index(room_min.x, y, z)
+				for x = room_min.x, room_max.x do
+					node_id = data[vi]
+					if node_id == c_netherrack or node_id == c_netherrack_deep then data[vi] = c_air end
+					vi = vi + 1
+				end
+			end
+		end
+	end
+
+	-- clear netherrack from dungeon stairways
+	if #rooms > 0 then
+		local stairPositions = minetest.find_nodes_in_area(area.MinEdge, area.MaxEdge, minetest.registered_biomes["nether_caverns"].node_dungeon_stair)
+		for _, stairPos in ipairs(stairPositions) do
+			vi = area:indexp(stairPos)
+			for i = 1, 4 do
+				if stairPos.y + i > area.MaxEdge.y then break end
+				vi = vi + area.ystride
+				node_id = data[vi]
+				-- searching forward of the stairs could also be done
+				if node_id == c_netherrack or node_id == c_netherrack_deep then data[vi] = c_air end
+			end
+		end
+	end
+end
+
+-- Since we already know where all the rooms and their walls are, and have all the nodes stored
+-- in a voxelmanip already, we may as well add a little Nether flair to the dungeons found here.
+nether.mapgen.decorate_dungeons = function(data, area, rooms)
+
+	local xStride, yStride, zStride = 1, area.ystride, area.zstride
+	local minEdge, maxEdge = area.MinEdge, area.MaxEdge
+
+	for _, roomInfo in ipairs(rooms) do
+
+		local room_min, room_max = roomInfo.minp, roomInfo.maxp
+		local room_size = vector.distance(room_min, room_max)
+
+		if room_size > 10 then
+			local room_seed = roomInfo.x + 3 * roomInfo.z + 13 * roomInfo.y
+			local window_y  = roomInfo.y + math_min(2, room_max.y - roomInfo.y - 1)
+			local roomWidth  = room_max.x - room_min.x + 1
+			local roomLength = room_max.z - room_min.z + 1
+
+			if room_seed % 3 == 0 and room_max.y < maxEdge.y then
+				-- Glowstone chandelier (feel free to replace with a fancy schematic)
+				local vi = area:index(roomInfo.x, room_max.y + 1, roomInfo.z)
+				if is_dungeon_brick(data[vi]) then data[vi] = c_glowstone end
+
+			elseif room_seed % 4 == 0 and room_min.y > minEdge.y
+				   and room_min.x > minEdge.x and room_max.x < maxEdge.x
+				   and room_min.z > minEdge.z and room_max.z < maxEdge.z then
+				-- lava well (feel free to replace with a fancy schematic)
+				local vi = area:index(roomInfo.x, room_min.y, roomInfo.z)
+				if is_dungeon_brick(data[vi - yStride]) then
+					data[vi - yStride] = c_lava_source
+					if data[vi - zStride] == c_air then data[vi - zStride] = c_netherbrick_slab end
+					if data[vi + zStride] == c_air then data[vi + zStride] = c_netherbrick_slab end
+					if data[vi - xStride] == c_air then data[vi - xStride] = c_netherbrick_slab end
+					if data[vi + xStride] == c_air then data[vi + xStride] = c_netherbrick_slab end
+				end
+			end
+
+			-- Barred windows
+			if room_seed % 7 < 5 and roomWidth >= 5 and roomLength >= 5
+			   and window_y >= minEdge.y and window_y + 1 <= maxEdge.y
+			   and room_min.x > minEdge.x and room_max.x < maxEdge.x
+			   and room_min.z > minEdge.z and room_max.z < maxEdge.z then
+				--data[area:indexp(roomInfo)] = minetest.get_content_id("default:mese_post_light") -- debug
+
+				-- Can't use glass panes because they need the param data set.
+				-- Until whisper glass is added, every window will be made of netherbrick fence (rather
+				-- than material depending on room_seed)
+				local window_node = c_netherfence
+				--if c_netherglass ~= nil and room_seed % 20 >= 12 then window_node = c_crystallight end
+
+				local function placeWindow(vi, viOutsideOffset, windowNo)
+					if is_dungeon_brick(data[vi]) and is_dungeon_brick(data[vi + yStride]) then
+						data[vi] = window_node
+
+						if room_seed % 19 == windowNo then
+							-- place a glowstone light behind the window
+							local node_id = data[vi + viOutsideOffset]
+							if node_id == c_netherrack then
+								data[vi + viOutsideOffset] = c_glowstone
+							elseif node_id == c_netherrack_deep then
+								data[vi + viOutsideOffset] = c_glowstone_deep
+							end
+						end
+					end
+				end
+
+				local vi_min = area:index(room_min.x - 1, window_y, roomInfo.z)
+				local vi_max = area:index(room_max.x + 1, window_y, roomInfo.z)
+				local locations = {-zStride, zStride, -zStride + yStride, zStride + yStride}
+				for i, offset in ipairs(locations) do
+					placeWindow(vi_min + offset, -1, i)
+					placeWindow(vi_max + offset,  1, i + #locations)
+				end
+				vi_min = area:index(roomInfo.x, window_y, room_min.z - 1)
+				vi_max = area:index(roomInfo.x, window_y, room_max.z + 1)
+				locations = {-xStride, xStride, -xStride + yStride, xStride + yStride}
+				for i, offset in ipairs(locations) do
+					placeWindow(vi_min + offset, -zStride, i + #locations * 2)
+					placeWindow(vi_max + offset,  zStride, i + #locations * 3)
+				end
+			end
+
+			-- pillars or mezzanine floor
+			if room_seed % 43 > 10 and roomWidth >= 6 and roomLength >= 6 then
+
+				local pillar_vi    = {}
+				local pillarHeight = 0
+				local wallDist = 1 + math.floor((roomWidth + roomLength) / 14)
+
+				local roomHeight = room_max.y - room_min.y
+				if roomHeight >= 7 then
+					-- mezzanine floor
+					local mezzMax = {
+						x = room_min.x + math.floor(roomWidth / 7 * 4),
+						y = room_min.y + math.floor(roomHeight / 5 * 3),
+						z = room_max.z
+					}
+
+					pillarHeight = mezzMax.y - room_min.y - 1
+					pillar_vi = {
+						area:index(mezzMax.x, room_min.y, room_min.z + wallDist),
+						area:index(mezzMax.x, room_min.y, room_max.z - wallDist),
+					}
+
+					if is_dungeon_brick(data[pillar_vi[1] - yStride]) and is_dungeon_brick(data[pillar_vi[2] - yStride]) then
+						-- The floor of the dungeon looks like it exists (i.e. not erased by nether
+						-- cavern), so add the mezzanine floor
+						for z = 0, roomLength - 1 do
+							local vi = area:index(room_min.x, mezzMax.y, room_min.z + z)
+							for x = room_min.x, mezzMax.x do
+								if data[vi] == c_air then data[vi] = c_dungeonbrick end
+								vi = vi + 1
+							end
+						end
+					end
+
+				elseif roomHeight >= 4 then
+					-- 4 pillars
+					pillarHeight = roomHeight
+					pillar_vi = {
+						area:index(room_min.x + wallDist, room_min.y, room_min.z + wallDist),
+						area:index(room_min.x + wallDist, room_min.y, room_max.z - wallDist),
+						area:index(room_max.x - wallDist, room_min.y, room_min.z + wallDist),
+						area:index(room_max.x - wallDist, room_min.y, room_max.z - wallDist)
+					}
+				end
+
+				for i = #pillar_vi, 1, -1 do
+					if not is_dungeon_brick(data[pillar_vi[i] - yStride]) then
+						-- there's no dungeon floor under this pillar so skip it, it's probably been cut away by nether cavern.
+						table.remove(pillar_vi, i)
+					end
+				end
+				for y = 0, pillarHeight do
+					for _, vi in ipairs(pillar_vi) do
+						if data[vi + y * yStride] == c_air then data[vi + y * yStride] = c_dungeonbrick end
+					end
+				end
+			end
+
+			-- Weeds on the floor once Nether weeds are added
+		end
+	end
+end
diff --git a/mods/world/nether/mapgen_mantle.lua b/mods/world/nether/mapgen_mantle.lua
index e453e19f..7883fb08 100644
--- a/mods/world/nether/mapgen_mantle.lua
+++ b/mods/world/nether/mapgen_mantle.lua
@@ -27,6 +27,7 @@
 
 local debugf = nether.debug
 local mapgen = nether.mapgen
+local S      = nether.get_translator
 
 local BASALT_COLUMN_UPPER_LIMIT = mapgen.BASALT_COLUMN_UPPER_LIMIT
 local BASALT_COLUMN_LOWER_LIMIT = mapgen.BASALT_COLUMN_LOWER_LIMIT
@@ -49,7 +50,6 @@ local np_basalt = {
 
 local nobj_basalt = nil
 local nbuf_basalt = {}
-local cavePerlin = nil
 
 -- Content ids
 
@@ -119,7 +119,7 @@ mapgen.add_basalt_columns = function(data, area, minp, maxp)
 	local yStride = area.ystride
 	local yCaveStride = x1 - x0 + 1
 
-	cavePerlin = cavePerlin or minetest.get_perlin(mapgen.np_cave)
+	local cavePerlin = mapgen.get_cave_point_perlin()
 	nobj_basalt = nobj_basalt or minetest.get_perlin_map(np_basalt, {x = yCaveStride, y = yCaveStride})
 	local nvals_basalt = nobj_basalt:get_2d_map_flat({x=minp.x, y=minp.z}, {x=yCaveStride, y=yCaveStride}, nbuf_basalt)
 
@@ -136,7 +136,7 @@ mapgen.add_basalt_columns = function(data, area, minp, maxp)
 			if basaltNoise > 0 then
 				-- a basalt column is here
 
-				local abs_sealevel_cave_noise = math_abs(cavePerlin:get3d({x = x, y = nearest_sea_level, z = z}))
+				local abs_sealevel_cave_noise = math_abs(cavePerlin:get_3d({x = x, y = nearest_sea_level, z = z}))
 
 				-- Add Some quick deterministic noise to the column heights
 				-- This is probably not good noise, but it doesn't have to be.
@@ -399,11 +399,14 @@ mapgen.excavate_tunnel_to_center_of_the_nether = function(data, area, nvals_cave
 	if lowest < mapgen.CENTER_CAVERN_LIMIT and highest > mapgen.TCAVE + 0.03 then
 
 		local mantle_y = area:position(lowest_vi).y
-		local sealevel, cavern_limit_distance = mapgen.find_nearest_lava_sealevel(mantle_y)
+		local _, cavern_limit_distance = mapgen.find_nearest_lava_sealevel(mantle_y)
 		local _, centerRegionLimit_adj = mapgen.get_mapgenblend_adjustments(mantle_y)
+
+		 -- cavern_noise_adj gets added to noise value instead of added to the limit np_noise
+		 -- is compared against, so subtract centerRegionLimit_adj instead of adding
 		local cavern_noise_adj =
 			mapgen.CENTER_REGION_LIMIT * (cavern_limit_distance * cavern_limit_distance * cavern_limit_distance) -
-			centerRegionLimit_adj -- cavern_noise_adj gets added to noise value instead of added to the limit np_noise is compared against, so subtract centerRegionLimit_adj instead of adding
+			centerRegionLimit_adj
 
 		if lowest + cavern_noise_adj < mapgen.CENTER_CAVERN_LIMIT then
 			excavate_pathway(data, area, area:position(highest_vi), area:position(lowest_vi), minp, maxp)
@@ -414,63 +417,96 @@ mapgen.excavate_tunnel_to_center_of_the_nether = function(data, area, nvals_cave
 end
 
 
+-- an enumerated list of the different regions in the nether
+mapgen.RegionEnum = {
+	OVERWORLD     = {name = "overworld",      desc = S("The Overworld") },   -- Outside the Nether / none of the regions in the Nether
+	POSITIVE      = {name = "positive",       desc = S("Positive nether") }, -- The classic nether caverns are here - where cavePerlin > 0.6
+	POSITIVESHELL = {name = "positive shell", desc = S("Shell between positive nether and center region") }, -- the nether side of the wall/buffer area separating classic nether from the mantle
+	CENTER        = {name = "center",         desc = S("Center/Mantle, inside cavern") },
+	CENTERSHELL   = {name = "center shell",   desc = S("Center/Mantle, but outside the caverns") }, -- the mantle side of the wall/buffer area separating the positive and negative regions from the center region
+	NEGATIVE      = {name = "negative",       desc = S("Negative nether") }, -- Secondary/spare region - where cavePerlin < -0.6
+	NEGATIVESHELL = {name = "negative shell", desc = S("Shell between negative nether and center region") } -- the spare region side of the wall/buffer area separating the negative region from the mantle
+}
+
+
+-- Returns (region, noise) where region is a value from mapgen.RegionEnum
+-- and noise is the unadjusted cave perlin value
+mapgen.get_region = function(pos)
+
+	if pos.y > nether.DEPTH_CEILING or pos.y < nether.DEPTH_FLOOR then
+		return mapgen.RegionEnum.OVERWORLD, nil
+	end
+
+	local caveNoise = mapgen.get_cave_perlin_at(pos)
+	local sealevel, cavern_limit_distance = mapgen.find_nearest_lava_sealevel(pos.y)
+	local tcave_adj, centerRegionLimit_adj = mapgen.get_mapgenblend_adjustments(pos.y)
+	local tcave   = mapgen.TCAVE + tcave_adj
+	local tmantle = mapgen.CENTER_REGION_LIMIT + centerRegionLimit_adj
+
+	-- cavern_noise_adj gets added to noise value instead of added to the limit np_noise
+	-- is compared against, so subtract centerRegionLimit_adj instead of adding
+	local cavern_noise_adj =
+		mapgen.CENTER_REGION_LIMIT * (cavern_limit_distance * cavern_limit_distance * cavern_limit_distance) -
+		centerRegionLimit_adj
+
+	local region
+	if caveNoise > tcave then
+		region = mapgen.RegionEnum.POSITIVE
+	elseif -caveNoise > tcave then
+		region = mapgen.RegionEnum.NEGATIVE
+	elseif math_abs(caveNoise) < tmantle then
+
+		if math_abs(caveNoise) + cavern_noise_adj < mapgen.CENTER_CAVERN_LIMIT then
+			region = mapgen.RegionEnum.CENTER
+		else
+			region = mapgen.RegionEnum.CENTERSHELL
+		end
+
+	elseif caveNoise > 0 then
+		region = mapgen.RegionEnum.POSITIVESHELL
+	else
+		region = mapgen.RegionEnum.NEGATIVESHELL
+	end
+
+	return region, caveNoise
+end
+
+
 minetest.register_chatcommand("nether_whereami",
-    {
-		description = "Describes which region of the nether the player is in",
+	{
+		description = S("Describes which region of the nether the player is in"),
 		privs = {debug = true},
 		func = function(name, param)
 
 			local player = minetest.get_player_by_name(name)
-			if player == nil then return false, "Unknown player position" end
+			if player == nil then return false, S("Unknown player position") end
+			local playerPos = vector.round(player:get_pos())
 
-			local pos = vector.round(player:get_pos())
-			if pos.y > nether.DEPTH_CEILING or pos.y < nether.DEPTH_FLOOR then
-				return true, "The Overworld"
-			end
+			local region, caveNoise                = mapgen.get_region(playerPos)
+			local seaLevel, cavernLimitDistance    = mapgen.find_nearest_lava_sealevel(playerPos.y)
+			local tcave_adj, centerRegionLimit_adj = mapgen.get_mapgenblend_adjustments(playerPos.y)
 
-			cavePerlin = cavePerlin or minetest.get_perlin(mapgen.np_cave)
-			local densityNoise = cavePerlin:get_3d(pos)
-			local sea_level, cavern_limit_distance = mapgen.find_nearest_lava_sealevel(pos.y)
-			local tcave_adj, centerRegionLimit_adj = mapgen.get_mapgenblend_adjustments(pos.y)
-			local tcave   = mapgen.TCAVE + tcave_adj
-			local tmantle = mapgen.CENTER_REGION_LIMIT + centerRegionLimit_adj
-			local cavern_noise_adj =
-				mapgen.CENTER_REGION_LIMIT * (cavern_limit_distance * cavern_limit_distance * cavern_limit_distance) -
-				centerRegionLimit_adj -- cavern_noise_adj gets added to noise value instead of added to the limit np_noise is compared against, so subtract centerRegionLimit_adj so subtract centerRegionLimit_adj instead of adding
+			local seaDesc = ""
+			local boundaryDesc = ""
+			local perlinDesc = ""
 
-			local desc
+			if region ~= mapgen.RegionEnum.OVERWORLD then
 
-			if densityNoise > tcave then
-				desc = "Positive nether"
-			elseif -densityNoise > tcave then
-				desc = "Negative nether"
-			elseif math_abs(densityNoise) < tmantle then
-				desc =  "Mantle"
-
-				if math_abs(densityNoise) + cavern_noise_adj < mapgen.CENTER_CAVERN_LIMIT then
-					desc =  desc .. " inside cavern"
+				local seaPos = playerPos.y - seaLevel
+				if seaPos > 0 then
+					seaDesc = S(", @1m above lava-sea level", seaPos)
 				else
-					desc =  desc .. " but outside cavern"
+					seaDesc = S(", @1m below lava-sea level", seaPos)
 				end
 
-			elseif densityNoise > 0 then
-				desc =  "Shell between positive nether and center region"
-			else
-				desc = "Shell between negative nether and center region"
+				if tcave_adj > 0 then
+					boundaryDesc = S(", approaching y boundary of Nether")
+				end
+
+				perlinDesc = S("[Perlin @1] ", (math_floor(caveNoise * 1000) / 1000))
 			end
 
-			local sea_pos = pos.y - sea_level
-			if sea_pos > 0 then
-				desc = desc .. ", " .. sea_pos .. "m above lava-sea level"
-			else
-				desc = desc .. ", " .. sea_pos .. "m below lava-sea level"
-			end
-
-			if tcave_adj > 0 then
-				desc = desc .. ", approaching y boundary of Nether"
-			end
-
-			return true, "[Perlin " .. (math_floor(densityNoise * 1000) / 1000) .. "] " .. desc
+			return true, S("@1@2@3@4", perlinDesc, region.desc, seaDesc, boundaryDesc)
 		end
 	}
 )
diff --git a/mods/world/nether/mapgen_nobiomes.lua b/mods/world/nether/mapgen_nobiomes.lua
index 28792b8c..1a371282 100644
--- a/mods/world/nether/mapgen_nobiomes.lua
+++ b/mods/world/nether/mapgen_nobiomes.lua
@@ -216,7 +216,7 @@ function nether.find_nether_ground_y(target_x, target_z, start_y, player_name)
 	local maxp = {x = maxp_schem.x, y = 0, z = maxp_schem.z}
 
 	for y = start_y, math.max(NETHER_FLOOR + BLEND, start_y - 4096), -1 do
-		local nval_cave = nobj_cave_point:get3d({x = target_x, y = y, z = target_z})
+		local nval_cave = nobj_cave_point:get_3d({x = target_x, y = y, z = target_z})
 
 		if nval_cave > TCAVE then -- Cavern
 			air = air + 1
diff --git a/mods/world/nether/mod.conf b/mods/world/nether/mod.conf
index 5b6c73a3..727c6f2c 100644
--- a/mods/world/nether/mod.conf
+++ b/mods/world/nether/mod.conf
@@ -1,4 +1,7 @@
 name = nether
 description = Adds a deep underground realm with different mapgen that you can reach with obsidian portals.
 depends = stairs, default
-optional_depends = moreblocks, mesecons, loot, dungeon_loot, doc_basics, fire
+optional_depends = moreblocks, mesecons, loot, dungeon_loot, doc_basics, fire, climate_api, ethereal
+release = 8686
+author = PilzAdam
+title = Nether
diff --git a/mods/world/nether/nether_api.txt b/mods/world/nether/nether_api.txt
new file mode 100644
index 00000000..40f86a57
--- /dev/null
+++ b/mods/world/nether/nether_api.txt
@@ -0,0 +1,78 @@
+Modding/interop guide to Nether
+===============================
+
+For portals API see portal_api.txt
+
+The Nether mod exposes some of its functions and data via the lua global
+`nether` and `nether.mapgen`
+
+
+* `nether.DEPTH_CEILING`: [read-only] Y value of the top of the Nether.
+
+* `nether.DEPTH_FLOOR`: [read-only] Y value of the bottom of the Nether.
+
+* `nether.DEPTH_FLOOR_LAYERS`: [writable] Gives the bottom Y of all
+  locations that wish to be considered part of the Nether.
+  DEPTH_FLOOR_LAYERS Allows mods to insert extra layers below the
+  Nether, by knowing where their layer ceiling should start, and letting
+  the layers be included in effects which only happen in the Nether.
+  If a mod wishes to add a layer below the Nether it should read
+  `nether.DEPTH_FLOOR_LAYERS` to find the bottom Y of the Nether and any
+  other layers already under the Nether. The mod should leave a small gap
+  between DEPTH_FLOOR_LAYERS and its ceiling (e.g. use DEPTH_FLOOR_LAYERS - 6
+  for its ceiling Y, so there is room to shift edge-case biomes), then set
+  `nether.DEPTH_FLOOR_LAYERS` to reflect the mod's floor Y value, and call
+  `shift_existing_biomes()` with DEPTH_FLOOR_LAYERS as the `floor_y` argument.
+
+* `nether.NETHER_REALM_ENABLED`: [read-only] Gets the value of the "Enable
+  Nether realm & portal" setting the nether mod exposes in Minetest's
+  "All Settings" -> "Mods" -> "nether" options.
+  When false, the entire nether mapgen is disabled (not run), and the portal
+  to it is not registered. Reasons someone might disable the Nether realm
+  include if a nether-layer mod was to be used as the Nether instead, or if
+  the portal mechanic was desired in a game without the Nether, etc.
+
+* `nether.useBiomes`: [read-only] When this is false, the Nether interop
+  functions below are not available (nil).
+  Indicates that the biomes-enabled mapgen is in use. The Nether mod falls back
+  to older mapgen code for v6 maps and old versions of Minetest, the older
+  mapgen code doesn't use biomes and doesn't provide API/interop functions.
+
+
+Mapgen functions available when nether.useBiomes is true
+--------------------------------------------------------
+
+The following functions are nil if `nether.useBiomes` is false,
+and also nil if `nether.NETHER_REALM_ENABLED` is false.
+
+* `nether.mapgen.shift_existing_biomes(floor_y, ceiling_y)` Move any existing
+  biomes out of the y-range specified by `floor_y` and `ceiling_y`.
+
+* `nether.mapgen.get_region(pos)`: Returns two values, (region, noise) where
+  `region` is a value from `nether.mapgen.RegionEnum` and `noise` is the
+  unadjusted cave perlin value.
+    * `nether.mapgen.RegionEnum` values are tables which contain an invariant
+      `name` and a localized `desc`. Current region names include overworld,
+      positive, positive shell, center, center shell, negative, and negative
+      shell.
+      "positive" corresponds to conventional Nether caverns, and "center"
+      corresponds to the Mantle region.
+
+* `nether.mapgen.get_cave_point_perlin()`: Returns the PerlinNoise object for
+  the Nether's cavern noise.
+
+* `nether.mapgen.get_cave_perlin_at(pos)`: Returns the Nether cavern noise
+  value at a given 3D position.
+
+
+Other mapgen functions
+-------------------------------------------
+
+If the Nether realm is enabled, then this function will be available
+regardless of whether `nether.useBiomes` is true:
+
+* `nether.find_nether_ground_y(target_x, target_z, start_y, player_name)`
+  Uses knowledge of the nether mapgen algorithm to return a suitable ground
+  level for placing a portal.
+    * `player_name` is optional, allowing a player to spawn a remote portal
+      in their own protected areas.
\ No newline at end of file
diff --git a/mods/world/nether/nodes.lua b/mods/world/nether/nodes.lua
index dea70701..073f6b0f 100644
--- a/mods/world/nether/nodes.lua
+++ b/mods/world/nether/nodes.lua
@@ -161,6 +161,13 @@ minetest.register_node("nether:fence_nether_brick", {
 	sounds = default.node_sound_stone_defaults(),
 })
 
+minetest.register_node("nether:brick_deep", {
+	description = S("Deep Nether Brick"),
+	tiles = {"nether_brick_deep.png"},
+	is_ground_content = false,
+	groups = {cracky = 2, level = 2},
+	sounds = default.node_sound_stone_defaults()
+})
 
 -- Register stair and slab
 
@@ -308,6 +315,8 @@ lavasea_source.tiles = {
 		},
 	},
 }
+lavasea_source.groups = { not_in_creative_inventory = 1 } -- Avoid having two lava source blocks in the inv.
+for key, value in pairs(lava_source.groups) do lavasea_source.groups[key] = value end
 lavasea_source.liquid_alternative_source = "nether:lava_source"
 lavasea_source.inventory_image = minetest.inventorycube(
 	"nether_lava_source_animated.png^[sheet:2x16:0,0",
@@ -327,8 +336,8 @@ nether.cool_lava = function(pos, node)
 
 	-- Evaporate water sitting above lava, if it's in the Nether.
 	-- (we don't want Nether mod to affect overworld lava mechanics)
-	if minetest.get_node_group(node_above.name, "water") > 0 and
-		pos.y < nether.DEPTH_CEILING and pos.y > nether.DEPTH_FLOOR then
+	if minetest.get_item_group(node_above.name, "water") > 0 and
+		pos.y < nether.DEPTH_CEILING and pos.y > nether.DEPTH_FLOOR_LAYERS then
 		-- cools_lava might be a better group to check for, but perhaps there's
 		-- something in that group that isn't a liquid and shouldn't be evaporated?
 		minetest.swap_node(pos_above, {name="air"})
@@ -374,7 +383,7 @@ minetest.register_on_mods_loaded(function()
 
 	-- register a bucket of Lava-sea source - but make it just the same bucket as default lava.
 	-- (by doing this in register_on_mods_loaded we don't need to declare a soft dependency)
-	if minetest.get_modpath("bucket") and minetest.global_exists("bucket") then
+	if minetest.get_modpath("bucket") and minetest.global_exists("bucket") and type(bucket.liquids) == "table" then
 		local lava_bucket = bucket.liquids["default:lava_source"]
 		if lava_bucket ~= nil then
 			local lavasea_bucket = {}
@@ -527,7 +536,7 @@ minetest.register_node("nether:lava_crust", {
 	paramtype = "light",
 	light_source = default.LIGHT_MAX - 3,
 	buildable_to = false,
-	walkable_to = true,
+	walkable = true,
 	is_ground_content = true,
 	drop = {
 		items = {{
@@ -595,7 +604,7 @@ local function fumarole_onTimer(pos, elapsed)
 
 	-- Fumaroles in the Nether can catch fire.
 	-- (if taken to the surface and used as cottage chimneys, they don't catch fire)
-	local inNether = pos.y <= nether.DEPTH and pos.y >= nether.DEPTH_FLOOR
+	local inNether = pos.y <= nether.DEPTH and pos.y >= nether.DEPTH_FLOOR_LAYERS
 	local canCatchFire = inNether and minetest.registered_nodes["fire:permanent_flame"] ~= nil
 	local smoke_offset   = 0
 	local timeout_factor = 1
diff --git a/mods/world/nether/portal_api.lua b/mods/world/nether/portal_api.lua
index 7dd2d547..c67b27d2 100644
--- a/mods/world/nether/portal_api.lua
+++ b/mods/world/nether/portal_api.lua
@@ -2007,7 +2007,8 @@ local wormhole_nodedef_default = {
 		a = 160, r = 128, g = 0, b = 80
 	},
 	sunlight_propagates = true,
-	use_texture_alpha = "blend",
+	use_texture_alpha = minetest.features.use_texture_alpha_string_modes
+		and "blend" or true,
 	walkable = false,
 	diggable = false,
 	pointable = false,
@@ -2015,7 +2016,6 @@ local wormhole_nodedef_default = {
 	is_ground_content = false,
 	drop = "",
 	light_source = 5,
-	alpha = 192,
 	node_box = {
 		type = "fixed",
 		fixed = {
@@ -2073,7 +2073,7 @@ function nether.register_portal(name, portaldef)
 	end
 
 	portaldef.name     = name
-	portaldef.mod_name = minetest.get_current_modname()
+	portaldef.mod_name = minetest.get_current_modname() or "<mod name not recorded>"
 
 	-- use portaldef_default for any values missing from portaldef or portaldef.sounds
 	if portaldef.sounds ~= nil then setmetatable(portaldef.sounds, {__index = portaldef_default.sounds}) end
@@ -2211,7 +2211,7 @@ function nether.volume_is_natural_and_unprotected(minp, maxp, player_name)
 			if id ~= c_air and id ~= c_ignore and id ~= nil then -- checked for common natural or not emerged
 				local name = minetest.get_name_from_content_id(id)
 				local nodedef = minetest.registered_nodes[name]
-				if not nodedef.is_ground_content then
+				if nodedef and not nodedef.is_ground_content then
 					-- trees are natural but not "ground content"
 					local node_groups = nodedef.groups
 					if node_groups == nil or (node_groups.tree == nil and node_groups.leaves == nil and node_groups.leafdecay == nil) then
diff --git a/mods/world/nether/portal_api.txt b/mods/world/nether/portal_api.txt
index ecac5005..15c82d83 100644
--- a/mods/world/nether/portal_api.txt
+++ b/mods/world/nether/portal_api.txt
@@ -250,16 +250,16 @@ Used by `nether.register_portal`.
         -- player_name may be "", e.g. if the portal was ignited by a mesecon,
         -- and is provided for use with volume_is_natural_and_unprotected() etc.
 
-        on_run_wormhole      = function(portalDef, anochorPos, orientation),
+        on_run_wormhole      = function(portalDef, anchorPos, orientation),
         -- invoked once per second per portal
-        on_extinguish        = function(portalDef, anochorPos, orientation),
+        on_extinguish        = function(portalDef, anchorPos, orientation),
         -- invoked when a portal is extinguished, including when the portal
         -- it connected to was extinguished.
         on_player_teleported = function(portalDef, player, oldPos, newPos),
         -- invoked immediately after a player is teleported
-        on_ignite            = function(portalDef, anochorPos, orientation)
+        on_ignite            = function(portalDef, anchorPos, orientation)
         -- invoked when a player or mesecon ignites a portal
-        on_created           = function(portalDef, anochorPos, orientation)
+        on_created           = function(portalDef, anchorPos, orientation)
         -- invoked when a portal creates a remote twin, this is usually when
         -- a player travels through a portal for the first time.
     }
diff --git a/mods/world/nether/portal_examples.lua b/mods/world/nether/portal_examples.lua
index ac71848a..663ee636 100644
--- a/mods/world/nether/portal_examples.lua
+++ b/mods/world/nether/portal_examples.lua
@@ -106,7 +106,7 @@ end
 -- Surface-travel portal, playable code example --
 --==============================================--
 
--- These Moore Curve functions requred by surface_portal's find_surface_anchorPos() will
+-- These Moore Curve functions required by surface_portal's find_surface_anchorPos() will
 -- be assigned later in this file.
 local get_moore_distance -- will be function get_moore_distance(cell_count, x, y): integer
 local get_moore_coords   -- will be function get_moore_coords(cell_count, distance): pos2d
diff --git a/mods/world/nether/textures/nether_brick_deep.png b/mods/world/nether/textures/nether_brick_deep.png
new file mode 100644
index 00000000..a11e53e4
Binary files /dev/null and b/mods/world/nether/textures/nether_brick_deep.png differ