A Stronghold is a generated underground structure, found beneath the surface of the Overworld.
Up to 128 strongholds spawn per map on Java Edition, as of 1.9 (only three spawn in the Xbox and PS3 editions). Most strongholds have a spawner (for silverfish), an abundance of stone bricks, torches, chests with randomized loot, Stone slabs, and blocks found mainly underground such as cobblestone.
A hazard worthy of note that is found inside strongholds is the silverfish. In addition to the spawner, some of the blocks the stronghold is composed of will spawn silverfish when broken; they are only distinguishable by their fixed mining speed, which is comparable to wool. Some of the items commonly found inside a stronghold include coal, apples, string, compasses, paper, books, iron bars, redstone, and sometimes a clock or gold ingots.
It is possible and relatively common for caverns, underground ravines, abandoned mineshafts, ocean monuments and dungeons to intersect a stronghold. It is also possible for stronghold hallways to extend out into a body of water, allowing for easier detection of the stronghold. When generated after 1.0.0, strongholds also contain a portal room with an inactive End portal, which when activated with 12 eyes of Ender, can be used to travel to the End.
Locating a stronghold
A Stronghold may be located using eyes of ender, which are crafted from an ender pearl and blaze powder. Several eyes of ender will most likely be needed.
The most basic method of locating the stronghold is to throw an eye of ender, which will float for a few blocks in the direction of the nearest stronghold before either dropping to the ground or (20% chance) shattering. If it does not shatter, the eye may be retrieved and thrown again. By throwing and following the eyes in this way, the stronghold can be located. It is recommended to travel in the direction the eye floated for a couple hundred blocks before throwing again, so that fewer eyes are lost to shattering. When the stronghold is nearby, the thrown eyes will fall in the same place repeatedly. The point can be verified by walking in different directions and re-throwing to verify the coordinates to which the eyes consistently float.
A more efficient means of locating the stronghold is triangulate from two different locations. The method of throwing and following eyes is used as above, but rather than following the eyes all the way to the stronghold, note your initial coordinates, throw eyes several times and follow them, until a next coordinate location 100 or so blocks apart are obtained. These two points will define a line, in the direction of the stronghold. A second line is needed, so this process should be repeated from another starting location, preferably some long distance away. By defining a second line of two coordinate points, the intercept of those two lines can be calculated and that intercept should be in the approximate location of the stronghold. By travelling to the intercept point, just a few thrown eyes of ender should lead to the specific location.
Either method will work reliably. The first requires more eyes of ender; while the second requires a little more geometry.
Tips for exploration
When exploring a stronghold, it is advised to bring some useful things.
- Pickaxe - there might be mossy stone bricks or ores (extremely rare) that could be useful to mine.
- Sword or other weapon - many mobs, including silverfish, may be encountered, so it is advised to bring a weapon.
- Eyes of Ender - the most important resource while exploring and finding a stronghold. These are required to find the stronghold and activate the End portal.
- Health Potions (Optional) - health may get low if attacked by hostile mobs. Regain health by using health potions.
- Iron or Diamond Armor - these kinds of armor are strong enough to keep a player alive while fighting enemies within a stronghold.
- Bow and several Arrows - this will be convenient later on in the End while fighting the ender dragon.
- Food - all the fighting and exploring will cause a player to lose several hunger points. Make sure to bring enough food items that restore at least 3 or more hunger points.
- Compass (Optional) - this could be used to help a player get their bearings and navigate the many rooms and corridors within a stronghold.
- Torches - like caves, strongholds are very dark inside. Plenty of torches will be needed.
- Bed (Recommended) - placing a bed in a stronghold and sleeping in it will allow a player to remain in the stronghold if they die, rather than running back from a long distance.
While there is no predefined template or blueprint for a stronghold, there are several rooms that may generate in a stronghold. Here is a list of the rooms and what they contain:
- Hall: big rooms that may contain a fountain. Often used as the entrance and/or to connect other rooms.
- Jail: empty rooms behind iron bars, iron doors (Usually opened) and buttons.
- Small library: small rooms that can contain bookshelves, wooden planks, chests and cobwebs.
- Large library: same as a small library, but with an added balcony above, and Fences and torches arranged in a chandelier-like style. Both floors are connected by ladders. There is also a chest on the balcony above.
- Empty rooms: these rooms are self-explanatory, and often generated to the sides of halls.
- End portal room: this room contains a deactivated End portal that is above lava and a silverfish spawner.
As a Base
If a player has visited a stronghold multiple times and knows the layout of the stronghold, they might want to use it as a secondary base. This has its advantages, but also disadvantages, which are detailed below:
- If playing on a server, it is very hard for "griefers" to find it if they don't have eyes of ender.
- Players don't have to build or dig a whole base because the map generator has already done the work for them.
- There is plenty of space to store loot and resources.
- A handy tip, if moving to another location, is to take anything that might be useful to have in a player's new base, including bricks.
- If a player gets lost in the overworld, they can find their base by using eyes of ender, so remember to take some when going out.
- If a player needs to go to the End (if the server does not have a warp feature that goes to the End), there is always an End portal nearby.
- Players will need lots of torches to ensure that no mobs will spawn. Otherwise, they must always be ready to fight.
- However, assuming they already have explored it thoroughly, there are likely already a lot of torches around.
- If playing in SMP, the last advantage also counts for other players armed with eyes of ender.
- Since they are often exposed by ravines, abandoned mine shafts, and dungeons, it makes it easier for griefers to find it. However, if a player blocks up the incidental entrances, they might just be able to make it harder for other players to stumble upon them.
- If a player is moving and following the tip named above, mining some stone bricks might awaken silverfish.
- An easy way to differentiate between normal bricks and silverfish bricks is to see how fast it mines with the player's hand. Silverfish bricks are destroyed in 3 seconds, even when players are using their hand.
- End portals become useless if there is an abandoned mine shaft or a ravine cutting right through it. This is because at least one of the 12 portal blocks tends to be destroyed on generation.
- There is a possibility that a player will be unable to locate the portal because it will be hidden inside the stones.
- It is extremely rare, but possible, for a dungeon to be just outside the portal room, thus cutting off the rest of the stronghold or not spawning it.
- If a stronghold is found at diamond level, there is a possibility that it will cut through bedrock. Usually, staircases going down to bedrock end up being just an empty room.
- Strongholds can sometimes spawn under oceans or other bodies of water. This occurrence can make them hard to access. However, if a passage is open while underwater, it will be easier to spot, particularly at night.
- Although it is extremely rare, an End portal in a stronghold has a 1/1,000,000,000,000 chance to already have all 12 eyes of ender fitted into the End portal frames, meaning a player can go to the End without even having to visit the Nether.
- As of April 2018, only one seed has been found to have this occurrence.
- In a pre-release for Minecraft 1.0, strongholds had glass pillars above their entrances and portal rooms.
- All monster eggs (naturally generated) in strongholds are in the form of regular stone bricks. Mossy and cracked variants, as well as exposed stone, can also be a monster egg, but only if a silverfish enters into them.