Nether Fortress

Fortress

Biomes	The Nether
Consists of	See Structure

{
    "title": "Fortress",
    "rows": [
        {
            "field": "The Nether",
            "label": "(link to Biome article, displayed as Biomes)"
        },
        {
            "field": "See (link to #Structure article, displayed as Structure)",
            "label": "Consists of"
        }
    ],
    "invimages": [],
    "images": [
        "Fortress.png"
    ]
}

Fortresses are structures that are naturally generated in the Nether.

Generation

Segments of a Nether fortress that are fully enclosed.

Fortresses tend to cluster together in strips that run along the Z-axis (north and south). Players who travel along the X-axis (east or west) will have the best chances of finding one; those who travel north or south may travel for hundreds or thousands of blocks before discovering a fortress.

Fortresses may be generated in inconvenient places, where half of or even the majority of the fortress is buried in netherrack. The interior will not be filled, however; all hallways and passages will be clear except for open walkways and bridges. It is rare, but possible for glowstone to generate inside of the fortress pathways.

Structure

The general pattern of the walkways.

A lava well found inside nether fortress.

Fortresses are very large bridge-like complexes, composed mainly of nether bricks, that are supported by massive pillars that tower high above the lava oceans. A fortress has two areas, an exterior area of open bridges and an interior area of enclosed corridors. Both the bridges and corridors can end in a "broken" structure or may simply end without elaboration. Fortresses can tunnel through netherrack, giving the "exterior" areas an appearance of tunnels with nether brick floor and netherrack walls and ceilings. At broken sections the terrain is not cleared, which may create a tunnel that leads straight into a wall of netherrack.

The exterior consists of:

• Straight bridges.
• Up to 5 plain four-way crossings.
• Up to 4 four-way crossings with arches made of nether brick and nether brick fence.
• Up to 4 small rooms with a single entrance, and full-block "stairs" leading to the roof which may have a single path leading out.
• Up to 2 blaze spawner platforms: structures consisting of three full-block "stairs" leading to a small platform fenced with nether brick fence, with a blaze spawner in the center.

Stairs in a nether fortress, with nether warts growing next to them.

The interior of the structures have 1×2 windows with nether brick fences as the windowpanes. The fences also form gate-like structures at the entrances of some rooms and corridors. Rooms include:

• The lava well room, which is the connection between the interior and exterior areas.
• Straight corridors.
• Up to 5 four-way crossings.
• Up to 20 corridor turns (10 right-turns and 10 left-turns), each with a ¹⁄₃ chance of having a loot chest in the corner.
• Up to 3 stairways (made from actual stair blocks) leading downwards.
• Up to 2 three-way intersections with a small exterior balcony.
• Up to 2 stairways leading up to an open landing, which have patches of soul sand and nether wart at the base of the stairs, a corridor leading away from the upper landing, and a corridor behind the stairs. If the room is generated embedded in netherrack, only one block above the landing is cleared.

Blocks

Block
Nether Bricks
Nether Brick Fence
Nether Brick Stairs
Soul Sand
Nether Wart
Chest
Blaze Spawner
Lava

Mobs

A blaze spawner generated into the side of some netherrack.

Fortresses use a list of possible mobs to spawn that is separate from the rest of the Nether. Fortresses spawn magma cubes at a much higher rate, and also spawn two exclusive mobs which cannot be found anywhere else: blazes and wither skeletons. Normal skeletons and zombie pigmen can also appear. Endermen do not spawn in fortresses.

The spawning algorithm has two checks:

1. It checks if the spawn coordinates are within the "bounding box" of a single piece (e.g. corridor or walkway) of the fortress. In this case the block type of the ground does not matter.
2. It checks if the spawn coordinates are within the "bounding box" of the entire fortress and whether the ground consists of nether bricks.

If either check passes, it uses the special mob list for fortresses rather than the general list for the Nether when choosing the mob to spawn. The actual mob spawning proceeds as normal for the mob chosen from this list.

Loot

A chest that generated in a fortress

Fortresses generate nether fortress loot with chests in the indoor sections placed at some corridor turns.

In Java Edition and Bedrock Edition, each nether fortress chest contains items drawn from 2 pools, with the following distribution:

Item	Stack Size		Weight		Chance	Avg. per chest	[hide] Avg. # chests to search
	2–4×	1×	2–4×	1×
Nothing	—	1	—	14⁄15	93.3%	0.933	1.1
Gold Ingot	1–3	—	15⁄73	—	49.0%	1.233	2.0
Saddle	1	—	10⁄73	—	35.3%	0.411	2.8
Golden Horse Armor	1	—	8⁄73	—	29.1%	0.329	3.4
Nether Wart	3–7	—	5⁄73	—	19.0%	1.027	5.3
Iron Ingot	1–5	—	5⁄73	—	19.0%	0.616	5.3
Diamond	1–3	—	5⁄73	—	19.0%	0.411	5.3
Flint and Steel	1	—	5⁄73	—	19.0%	0.205	5.3
Iron Horse Armor	1	—	5⁄73	—	19.0%	0.205	5.3
Golden Sword	1	—	5⁄73	—	19.0%	0.205	5.3
Golden Chestplate	1	—	5⁄73	—	19.0%	0.205	5.3
Diamond Horse Armor	1	—	3⁄73	—	11.8%	0.123	8.5
Obsidian	2–4	—	2⁄73	—	8.0%	0.247	12.5
Rib Armor Trim Smithing Template	—	1	—	1⁄15	6.7%	0.067	15.0

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], "sortsize": [ 1, 0 ], "sortweight": [ 3, 0 ], "weights": [ "<sup>3</sup>&frasl;<sub>73</sub>", "—" ], "avgamount": 0.1232876712328767, "chanceany": 0.1177728226195418 }, "rib-armor-trim-smithing-template": { "itemname": "rib-armor-trim-smithing-template", "sizes": [ "—", 1 ], "sortsize": [ 0, 1 ], "sortweight": [ 0, 1 ], "weights": [ "—", "<sup>1</sup>&frasl;<sub>15</sub>" ], "avgamount": 0.06666666666666667, "chanceany": 0.06666666666666665 }, "obsidian": { "itemname": "obsidian", "sizes": [ "2–4", "—" ], "sortsize": [ 3, 0 ], "sortweight": [ 2, 0 ], "weights": [ "<sup>2</sup>&frasl;<sub>73</sub>", "—" ], "avgamount": 0.2465753424657534, "chanceany": 0.07972383453843734 }, "gold-ingot": { "itemname": "gold-ingot", "sizes": [ "1–3", "—" ], "sortsize": [ 2, 0 ], "sortweight": [ 15, 0 ], "weights": [ "<sup>15</sup>&frasl;<sub>73</sub>", "—" ], "avgamount": 1.2328767123287672, "chanceany": 0.48956430083116764 }, "empty": { "itemname": "empty", "sizes": [ "—", 1 ], "sortsize": [ 0, 1 ], "sortweight": [ 0, 14 ], "weights": [ "—", "<sup>14</sup>&frasl;<sub>15</sub>" ], "avgamount": 0.9333333333333333, "chanceany": 0.9333333333333333 }, "saddle": { "sortsize": [ 1, 0 ], "weights": [ "<sup>10</sup>&frasl;<sub>73</sub>", "—" ], "chanceany": 0.35257500631817307, "sizes": [ 1, "—" ], "sortweight": [ 10, 0 ], "armor": 0, "material": 0, "avgamount": 0.410958904109589, "itemname": "saddle" }, "golden-chestplate": { "sortsize": [ 1, 0 ], "weights": [ "<sup>5</sup>&frasl;<sub>73</sub>", "—" ], "chanceany": 0.1903699481480795, "sizes": [ 1, "—" ], "sortweight": [ 5, 0 ], "armor": 2, "material": 3, "avgamount": 0.2054794520547945, "itemname": "golden-chestplate" }, "iron-horse-armor": { "sortsize": [ 1, 0 ], "weights": [ "<sup>5</sup>&frasl;<sub>73</sub>", "—" ], "chanceany": 0.1903699481480795, "sizes": [ 1, "—" ], "sortweight": [ 5, 0 ], "armor": 0, "material": 2, "avgamount": 0.2054794520547945, "itemname": "iron-horse-armor" }, "iron-ingot": { "itemname": "iron-ingot", "sizes": [ "1–5", "—" ], "sortsize": [ 3, 0 ], "sortweight": [ 5, 0 ], "weights": [ "<sup>5</sup>&frasl;<sub>73</sub>", "—" ], "avgamount": 0.6164383561643836, "chanceany": 0.1903699481480795 }, "golden-sword": { "sortsize": [ 1, 0 ], "weights": [ "<sup>5</sup>&frasl;<sub>73</sub>", "—" ], "chanceany": 0.1903699481480795, "sizes": [ 1, "—" ], "sortweight": [ 5, 0 ], "armor": 0, "material": 3, "avgamount": 0.2054794520547945, "itemname": "golden-sword" }, "golden-horse-armor": { "itemname": "golden-horse-armor", "sizes": [ 1, "—" ], "sortsize": [ 1, 0 ], "sortweight": [ 8, 0 ], "weights": [ "<sup>8</sup>&frasl;<sub>73</sub>", "—" ], "avgamount": 0.3287671232876712, "chanceany": 0.2908800818567131 }, "flint-and-steel": { "sortsize": [ 1, 0 ], "weights": [ "<sup>5</sup>&frasl;<sub>73</sub>", "—" ], "chanceany": 0.1903699481480795, "sizes": [ 1, "—" ], "sortweight": [ 5, 0 ], "armor": 0, "material": 0, "avgamount": 0.2054794520547945, "itemname": "flint-and-steel" }, "nether-wart": { "itemname": "nether-wart", "sizes": [ "3–7", "—" ], "sortsize": [ 5, 0 ], "sortweight": [ 5, 0 ], "weights": [ "<sup>5</sup>&frasl;<sub>73</sub>", "—" ], "avgamount": 1.0273972602739727, "chanceany": 0.1903699481480795 } }, "display_name": "nether fortress", "structID": "nether-fortress", "poolsJavaUpcoming": [], "structure": "Nether Fortress", "container": "", "itemDataJavaUpcoming": [], "allRollsJavaUpcoming": [], "itemDataBedrock": { "diamond": { "itemname": "diamond", "sizes": [ "1–3", "—" ], "sortsize": [ 2, 0 ], "sortweight": [ 5, 0 ], "weights": [ "<sup>5</sup>&frasl;<sub>73</sub>", "—" ], "avgamount": 0.410958904109589, "chanceany": 0.1903699481480795 }, "diamond-horse-armor": { "itemname": "diamond-horse-armor", "sizes": [ 1, "—" ], "sortsize": [ 1, 0 ], "sortweight": [ 3, 0 ], "weights": [ "<sup>3</sup>&frasl;<sub>73</sub>", "—" ], "avgamount": 0.1232876712328767, "chanceany": 0.1177728226195418 }, "rib-armor-trim-smithing-template": { "itemname": "rib-armor-trim-smithing-template", "sizes": [ "—", 1 ], "sortsize": [ 0, 1 ], "sortweight": [ 0, 1 ], "weights": [ "—", "<sup>1</sup>&frasl;<sub>15</sub>" ], "avgamount": 0.06666666666666667, "chanceany": 0.06666666666666665 }, "obsidian": { "itemname": "obsidian", "sizes": [ "2–4", "—" ], "sortsize": [ 3, 0 ], "sortweight": [ 2, 0 ], "weights": [ "<sup>2</sup>&frasl;<sub>73</sub>", "—" ], "avgamount": 0.2465753424657534, "chanceany": 0.07972383453843734 }, "gold-ingot": { "itemname": "gold-ingot", "sizes": [ "1–3", "—" ], "sortsize": [ 2, 0 ], "sortweight": [ 15, 0 ], "weights": [ "<sup>15</sup>&frasl;<sub>73</sub>", "—" ], "avgamount": 1.2328767123287672, "chanceany": 0.48956430083116764 }, "empty": { "itemname": "empty", "sizes": [ "—", 1 ], "sortsize": [ 0, 1 ], "sortweight": [ 0, 14 ], "weights": [ "—", "<sup>14</sup>&frasl;<sub>15</sub>" ], "avgamount": 0.9333333333333333, "chanceany": 0.9333333333333333 }, "saddle": { "sortsize": [ 1, 0 ], "weights": [ "<sup>10</sup>&frasl;<sub>73</sub>", "—" ], "chanceany": 0.35257500631817307, "sizes": [ 1, "—" ], "sortweight": [ 10, 0 ], "armor": 0, "material": 0, "avgamount": 0.410958904109589, "itemname": "saddle" }, "golden-chestplate": { "sortsize": [ 1, 0 ], "weights": [ "<sup>5</sup>&frasl;<sub>73</sub>", "—" ], "chanceany": 0.1903699481480795, "sizes": [ 1, "—" ], "sortweight": [ 5, 0 ], "armor": 2, "material": 3, "avgamount": 0.2054794520547945, "itemname": "golden-chestplate" }, "iron-horse-armor": { "sortsize": [ 1, 0 ], "weights": [ "<sup>5</sup>&frasl;<sub>73</sub>", "—" ], "chanceany": 0.1903699481480795, "sizes": [ 1, "—" ], "sortweight": [ 5, 0 ], "armor": 0, "material": 2, "avgamount": 0.2054794520547945, "itemname": "iron-horse-armor" }, "iron-ingot": { "itemname": "iron-ingot", "sizes": [ "1–5", "—" ], "sortsize": [ 3, 0 ], "sortweight": [ 5, 0 ], "weights": [ "<sup>5</sup>&frasl;<sub>73</sub>", "—" ], "avgamount": 0.6164383561643836, "chanceany": 0.1903699481480795 }, "golden-sword": { "sortsize": [ 1, 0 ], "weights": [ "<sup>5</sup>&frasl;<sub>73</sub>", "—" ], "chanceany": 0.1903699481480795, "sizes": [ 1, "—" ], "sortweight": [ 5, 0 ], "armor": 0, "material": 3, "avgamount": 0.2054794520547945, "itemname": "golden-sword" }, "golden-horse-armor": { "itemname": "golden-horse-armor", "sizes": [ 1, "—" ], "sortsize": [ 1, 0 ], "sortweight": [ 8, 0 ], "weights": [ "<sup>8</sup>&frasl;<sub>73</sub>", "—" ], "avgamount": 0.3287671232876712, "chanceany": 0.2908800818567131 }, "flint-and-steel": { "sortsize": [ 1, 0 ], "weights": [ "<sup>5</sup>&frasl;<sub>73</sub>", "—" ], "chanceany": 0.1903699481480795, "sizes": [ 1, "—" ], "sortweight": [ 5, 0 ], "armor": 0, "material": 0, "avgamount": 0.2054794520547945, "itemname": "flint-and-steel" }, "nether-wart": { "itemname": "nether-wart", "sizes": [ "3–7", "—" ], "sortsize": [ 5, 0 ], "sortweight": [ 5, 0 ], "weights": [ "<sup>5</sup>&frasl;<sub>73</sub>", "—" ], "avgamount": 1.0273972602739727, "chanceany": 0.1903699481480795 } }, "poolsBedrock": [ { "items": { "diamond": [ 1, 3, 5 ], "saddle": [ 1, 1, 10 ], "obsidian": [ 2, 4, 2 ], "gold-ingot": [ 1, 3, 15 ], "diamond-horse-armor": [ 1, 1, 3 ], "golden-chestplate": [ 1, 1, 5 ], "iron-horse-armor": [ 1, 1, 5 ], "golden-horse-armor": [ 1, 1, 8 ], "golden-sword": [ 1, 1, 5 ], "iron-ingot": [ 1, 5, 5 ], "flint-and-steel": [ 1, 1, 5 ], "nether-wart": [ 3, 7, 5 ] }, "rolls": [ 2, 4 ], "totalweight": 73 }, { "items": { "empty": [ 1, 1, 14 ], "rib-armor-trim-smithing-template": [ 1, 1, 1 ] }, "rolls": [ 1, 1 ], "totalweight": 15 } ], "allRollsBedrockUpcoming": [], "allRollsBedrock": [ "2–4", 1 ], "itemDataBedrockUpcoming": [], "header": "[[Nether Fortress]]", "allRollsJava": [ "2–4", 1 ], "link": "[[nether fortress]]" } } }

Advancements

Icon	Advancement	In-game description	Actual requirements (if different)
	A Terrible Fortress	Break your way into a Nether Fortress	Enter a nether fortress.

Video

Nether Fortress/video

History

[hide]Java Edition
1.0.0							Jens Bergensten tweets a teaser screenshot of changes to the Nether terrain generation, including fortresses. {"type": "java", "version": "1.0.0", "exp": "", "snap": "", "content": "(link to Jens Bergensten article, displayed as Jens Bergensten) tweets a teaser screenshot of changes to the Nether terrain generation, including fortresses."}
							Jens releases a second teaser screenshot, showcasing the structure of the upcoming fortresses. {"type": "java", "version": "", "exp": "", "snap": "", "content": "Jens releases a second teaser screenshot, showcasing the structure of the upcoming fortresses."}
							Jens mentions that he is finished with most of the new Nether features, including two new mobs, one of which is a "retexturing attempt". {"type": "java", "version": "", "exp": "", "snap": "", "content": "Jens mentions that he is finished with most of the new Nether features, including two new mobs, one of which is a \"retexturing attempt\"."}
							Added fortresses. {"type": "java", "version": "", "exp": "", "snap": "", "content": "Added fortresses."}
1.4.2							Wither skeletons and skeletons will now naturally spawn in fortresses. {"type": "java", "version": "1.4.2", "exp": "", "snap": "", "content": "(link to Wither skeleton article, displayed as Wither skeletons) and (link to skeleton article, displayed as skeletons) will now naturally spawn in fortresses."}
							Other mobs also found in fortresses spawn less often due to that addition. Zombie pigmen became remarkably more uncommon though due to their weight being halved. {"type": "java", "version": "1.4.2", "exp": "", "snap": "", "content": "Other mobs also found in fortresses spawn less often due to that addition. (link to Zombie pigmen article, displayed as Zombie pigmen) became remarkably more uncommon though due to their weight being halved."}
1.6.1							Chests will now generate. {"type": "java", "version": "1.6.1", "exp": "", "snap": "", "content": "Chests will now generate."}
1.8							Fortresses are now affected by the "Generated structures" option. {"type": "java", "version": "1.8", "exp": "", "snap": "", "content": "Fortresses are now affected by the \"Generated structures\" option."}
							Added possibility of obsidian in chests. {"type": "java", "version": "", "exp": "", "snap": "", "content": "Added possibility of obsidian in chests."}
1.9							Reduced loot in chests from 2–5 stacks to 2–4. {"type": "java", "version": "1.9", "exp": "", "snap": "", "content": "Reduced loot in chests from 2–5 stacks to 2–4."}
[hide]Pocket Edition Alpha
0.12.1							Added fortresses. {"type": "pocket Alpha", "version": "0.12.1", "exp": "", "snap": "", "content": "Added fortresses."}
0.15.0							Horse Armor can be found in chest loot. {"type": "pocket Alpha", "version": "0.15.0", "exp": "", "snap": "", "content": "Horse Armor can be found in chest loot."}
[hide]Legacy Console Edition
Xbox 360	Xbox One	PS3	PS4	PS Vita	Wii U	Switch
TU7	CU1				Patch 1		Added fortresses. {"type": "console", "xbox": "TU7", "xbone": "CU1", "ps3": "", "ps4": "", "psvita": "", "wiiu": "Patch 1", "switch": "", "content": "Added fortresses."}
TU9							Changed fortresses to make nether wart rooms more likely. {"type": "console", "xbox": "TU9", "xbone": "", "ps3": "", "ps4": "", "psvita": "", "wiiu": "", "switch": "", "content": "Changed fortresses to make nether wart rooms more likely."}
TU19	CU7						Chests will now generate. {"type": "console", "xbox": "TU19", "xbone": "CU7", "ps3": "", "ps4": "", "psvita": "", "wiiu": "", "switch": "", "content": "Chests will now generate."}
[hide]New Nintendo 3DS Edition
0.1.0							Added fortresses. {"type": "new3ds", "version": "0.1.0", "exp": "", "snap": "", "content": "Added fortresses."}

Issues

Issues relating to "Nether Fortress" are maintained on the bug tracker. Issues should be reported and viewed there.

Trivia

• In extremely rare cases, a fortress will not generate any indoor rooms except one single lava room.
• Sometimes, two or more fortresses can generate very close or even within each other, ultimately creating an even larger cumulative fortress.
• Inside of the lava well (not the room), there is an opening out of the fortress, with a single block of nether bricks from which the lava spreads out.

Gallery

• 

  First screenshot released of the structures.

• 

  Brightened version of the previous screenshot.

• 

  An early image of fortresses released by Jeb.

• 

  Brightened.

• 

  Some nether warts found at a stair.

• 

  Demonstration of the pathway architecture and its ability to cut through netherrack.

• 

  The blaze spawner room.

• 

  The abrupt end of an inside corridor.

• 

  Broken walkways.

• 

  A large amount of corridors. Notice how corridors do not develop arches in their supports.

• 

  A close up view of the size and beauty of the fortress.

• 

  A ghast that has spawned inside of one of the larger rooms.

• 

  Another ghast spawned inside a fortress' player expanded room.

• 

  A player in a fortress with another nether fortress across from it.

• 

  A fortress with another one generated on top of it.

• 

  The lava well room.