Caverns, tunnels, or caves are commonly-found cavities in the stone layer of a map. Many caverns have tunnels branching off (called catacombs) and winding in other directions, some of which connect to the surface of the map creating natural entries to the cavern. Caverns can be quite deep, extending from the surface all the way to the bedrock layer. These caverns are randomly generated so two of them will almost never look exactly alike, making guides difficult to write. They can sometimes be attached to natural dungeons.
Caverns usually contain at least one type of exposed ore block. Hostile mobs often spawn in naturally occurring caverns because of its low light level so it is advisable to bring along a weapon if on any difficulty other than peaceful. Exposed cave systems are most often found in mountain biomes.
Caverns can be useful as a starting point for creating player-made dungeons and other underground structures. Since natural caverns have areas of exposed rock, they can save quite a bit of time while searching for ore. However, caverns can be quite deep, like pits, so accidentally breaking into one from above could inflict a lot of fall damage. Players should be aware of the potential presence of lava as it is one of the main risk factors of exploring caverns, even on peaceful.
A pit is a hole in the ground that falls straight down. Pits are usually found in caverns or when mining down you may fall into one. Pits are a good way to go farther underground, but are dangerous because they can lead into lava, a dungeon, or the fall may kill the player. It is advised that the player should bring a bucket of water or ladders which can be used to create a water elevator or stairway before exploring a pit. If you fall in a pit of lava you will most likely die and any items in your inventory will be burned. However, lava pools are only common below Y-layer 13. Technically caves are simply pockets of air (ignoring fluids, lava lakes and water lakes). This explains the "Dud" caves and caves that appear to "skim" the surface.
 Finding caverns
There are a number of ways to find caverns. Below is a table, designed to make cavern-hunting easier.
|Exploring Surface||By exploring the surface of the map, there is a good chance that an exposed cavern can be found.|
|Digging||Digging around might uncover caverns, but it is not easy as the map is (very) large. Choosing a random location and digging a tunnel straight down will intersect a cave system roughly half the time. A diagonal tunnel (downward staircase) takes 3 times as long to dig, but is much safer and can be traversed both ways. Make sure to look out for dripping water or lava above you as it hints at a lake. You can also find caves by quarrying on layer 12 and have your exploration much more profitable rather than only having cut through ore veins that contain less. Quarrying on layer 12 can get you diamonds and lava pools too.|
|Listening||By following the source of ambience, or the sound of mobs coming from underground, there is a great chance to find a cavern. It's also useful to follow sound of water. Lava makes a sound as well, which can be useful in finding diamonds, since lava and diamonds can be found in the same layers underground.|
|Piston||Dig down, place a piston and power it. Since pistons don't extend if there are 13+ blocks ahead of them, you can use pistons to find caves.|
|The Nether||Traveling to The Nether, going down roughly 20-30 blocks, and creating a new portal will likely cause the new Overworld portal to spawn in a cavern since a portal is spawned in the nearest suitable space for the portal.|
|Cartographer||Use 3rd party software (such as Cartograph) to make maps of caves. This can easily lead the player to Dungeons or Caverns. This is considered cheating by some players.|
|Editing "terrain.png"||Using an image editing program to delete the grass texture from the terrain.png file and using it as a texture pack will result in grass being see-through when loaded in game, allowing the player to see all underground caves from the surface without digging or coordinating maps. This is also considered cheating by some players and might get the player banned on multiplayer servers. Performing this trick with a lesser used block instead, like wool, will act as a 'portable window' allowing you to view adjacent tunnels while in a cave, as well as simple location. Leaving a portion of the texture intact will make such blocks easier to find. There are also texture packs that do this, erasing most textures besides ores and liquids.|
|TNT-Piston Glitch||Dig a 3 block wide by two block deep hole into a vertical wall. Place 2 sticky pistons on top of one another at one corner of the hole. Place 2 TNT in front of the pistons. Place a block on the ground next to the bottom piston, and put a lever on top of it. Make sure the lever isn't directly adjacent to the TNT! Stand between the piston and the side of the hole and you will be able to see any cave in the nearby area when you pull the lever. Another form, but with the same idea is to dig a hole in the ground straight down. Then dig to the side (either side) and place a lever. Place redstone dust one block straight, and then to the side you want your piston on. Place two red stone dust here. Then place your piston, and then your TNT. Dig down one block in front of your TNT, and then pull the lever.
This also works with glowstone instead of TNT, but glowstone is less portable than TNT, because it drops 4 or less dust when broken. On the other hand, glowstone doesn't explode!
|Tree Glitch||You will need a sapling and bonemeal. First, dig 2 deep straight down, place dirt in the hole and plant a sapling on it. Then stand next to it and use bone meal. You can see through the leaves so you can find any caves or lava lakes. This only works on "fast" graphics setting.|
- It is surprisingly easy to get lost in caverns. Below are a number of methods you can implement while exploring to prevent this, especially trail markers. The Navigation tutorial has much more information about markers and other navigation methods. (Summary: Torches, wool, signs, blocks and arrows made from them, and especially jack-o-lanterns.)
- One fairly easy marker method is the "torch on the right" rule. While exploring a cave simply place torches on the right side of the wall as you go deeper in. This way, no matter how complicated and even intertwined the caves get, you can always find your way back because if the torch is on the left of a cave wall, that means you're heading towards the exit and if it's on the right it means you're heading deeper in
- While it will not help you in navigating the cave itself, it may be wise to bring a map with you into a large cave, should you get lost and need to dig your way out. Note that most caves occupy less area horizontally than they might seem, but interconnected caves and abandoned mineshafts can sprawl over huge distances. You might well map some new surface as you explore underground, but the cave itself will not be mapped.
- An important tip to remember in caves is to always look around, especially upwards. One of the most common sources of mobs within previously explored caves is unnoticed openings in the ceiling or walls. If you're in a ravine, watch out for monsters falling off of high ledges!
- A good mining practice is to fully explore and light a cave system before beginning to mine out any resources. It is extremely dangerous to stop and mine in a dark cave system, and you can lose your loot if you are killed. Check for "broken bridges" such as gravel masses or 2-block drops. If monsters can come out of them, you may want to change that; once verified safe, you can save the blocked-off areas for later.
- As part of exploration, "clean up" the area, taking off leftover blocks, filling small pits, and generally smoothing things out. In abandoned mineshafts, you can clear out most of the fence-and-plank "supports" as you "claim" an area. This will use a lot of axes, but it will improve both visibility and mobility, cutting down on unpleasant surprises. (Notably, those fences provide better cover for creepers than they do for you!)
- To reach ores or tunnels high on the ceiling, try pillar jumping to gain altitude. You can also build bridges across ravines and pits.
- Water coming down from above is especially troublesome, as it can carry monsters down from a whole chain of darkened caverns.
- It's a good idea to swim upwards and light the path of the flow.
- Most water flows can be captured at the source with a bucket; if that doesn't work out, they can be contained with fences or blocks. Either way, be aware of areas where the water flow formerly blocked monsters! Some flows may be useful to keep for travel—you can swim up or down waterfalls to traverse high cliffs. With a little care, you can swim along the outside of the waterfall, which lets you keep breathing normally.
- Some water flows come from openings in the seafloor. With care (and perhaps a door or some ladders), you can swim up these and mark the entrance with a jack-o-lantern, which will generally be visible from the sea surface. Such openings are also a quick way to get back to the surface if you've gotten lost. With a bit more effort, you can seal the opening altogether, perhaps leaving a shaft with ladders for your own use. (Remember that ladders and signs block water.)
- Lava flows and pools can also block your passage as well as the monsters'. Like water, lava flows can be bucketed if you can reach the source, or contained with blocks otherwise. Lava pools can be flooded to convert them to obsidian. Again, be aware of areas where monsters were blocked by the lava. Also, remember to re-light the area after removing that brightly glowing lava.
- When finished exploring a cave, you can make your own exit—just dig upwards to the surface in a staircase fashion, watching for drips. You can also dig directly upwards, however, be careful when doing so, as it can cause suffocation.
- When digging a staircase out of a cave, it can be useful to check your map to figure out where you will, or want to, emerge. Coming out into the seabed can be tricky, especially if your torches get washed away.
 Classification of caverns
A cavern can be classified into the following kinds of cave systems.
 Small cavern (dud cavern)
Small caverns are primarily located close to sea level and are unlikely to be linked with other caverns. They frequently contain small deposits of basic ores such as coal and iron whilst seldom possessing rarer materials. Such caverns may have multiple entrances which are naturally lit. This type of cave also commonly has a pool of water in it, likely caused by the generation of the water itself.
 Medium cave (splatter cave)
Medium sized cave systems are commonly found within reach of other, often smaller, bountiful caverns which are accessible via mining. These caverns frequently contain large deposits of basic ores alongside small repositories of rarer materials - including Lapis Lazuli and Gold. Splatter caves also regularly contain, at the very least, minor water or lava flows as well as the presence of small dungeons.
 Large cave (Monster Nest)
Large subterranean systems, found deep within the earth close to the bedrock, hold large deposits of essentially every known type of ore - with rarer materials, such as Diamond, being found, like everywhere else, in less frequent deposits than more common materials. Such systems contain a number of large lakes as well as the presence of major lava flows. Furthermore, exploring large caverns is often rather hard, due to the huge volume of naturally generated tunnels often part of epic caverns. It is sometimes thought that hostile mobs spawn more often here, but that is probably due to the fact that you can see farther in Large caves that in other types of caverns. It is common for dungeons to be found within these systems. Also large caves are very hard to explore due to medium and small caves spawning nearby. It is best to explore with other players in a large cave, because it is very easy to get lost or confused.
 Circular rooms
During the terrain generation process large symmetrical and cylindrical chambers of various sizes can infrequently be created underground which often merge with other cave systems. These "rooms" vary from roughly 5 to 22 blocks in height, and from roughly 11 to over 30 blocks in width and/or length, though the latter is quite rare. Although not particularly of interest, from a mining perspective, they may appear unnatural and irregular in comparison to the surrounding terrain. While the smallest rarely contain many ores, the largest can be quite useful for mining as their sheer surface area rivals that of a medium-large ravine. Very rarely, a dungeon can be found in these rooms. Circular rooms can make good underground bases, just make sure you block off any other entrances and have a way for mobs to not get in.
- Main article: Generated structures#Ravines
These are natural formations of stone and gravel that can cross a big part of an island. It's rather deep, and sometimes can connect with any kind of cave, even with dungeons and sometimes abandoned mine shafts or, much rarer, strongholds. To ensure safety while proceeding downwards, use sand and gravel to drop down and create a basic elevator. You may also want to simply descend down a waterfall. In the ravine, fair amounts of coal and iron ore can be found. Due to the fact the ravines are fairly deep drops, a good ten minutes may find a deposit of gold or rarely, diamond. Ravines were first introduced in the Beta 1.8 Adventure Update. It is very possible to die in ravines due to the large drops and connections to caves.
 Deep cliff
A deep cavern sometimes goes down onto bedrock. This formation is not to be confused with a ravine, although they can be quite similar. These caverns are usually not linked to other caverns and don't have large amounts of minerals in them. Dungeons usually aren't linked to them because they are generated almost straight down and the bottom is often in full sunlight. This makes it hard for hostile mobs to spawn there. They are very useful for making traps or to lure mobs to fall to their deaths and safely collect their drops at the bottom.
 Giant entrance (Wormhole)
These caverns have a large hole for an entrance and then often spiral down, containing materials like coal and iron. These are not that rare and if you look hard enough, you can find one. Rarely, these entrances can go nearly straight down, exposing rare minerals like gold and lapis lazuli.
 Sea-access cave
These caves are often connected with the sea, and can be accessed from the sea. These were most common in Minecraft Classic. These act like a horizontal underwater giant entrance to a splatter cave that often contains lava, allowing them to be seen from the surface of the ocean.
Caverns are huge and have lots of intersecting tunnels, making them common to get lost in. Getting lost in a cavern can be very dangerous. If lost too long you may run out of food or weapons and starve or get killed.
These are some of the recommended items you should bring with you into caverns.
Weapons: Because of a caverns low light level, mobs such as zombies, spiders, skeletons, etc., will spawn in them making exploration dangerous. It is recommended the player brings weapons such as swords, axes, or bows and arrows to fight off monsters.
Tools: Because of caverns being found at stone level, lots of ores such as iron, coal, gold, redstone, lapis, or on rare occasions, diamonds or emeralds. So it is recommended you bring pickaxes with you to mine ores. Also be sure to bring shears with you in case you run into an abandoned mine shaft. You can use shears to destroy cobwebs without using your sword.
Light: Caverns can be very dark. Always remember to bring light sources with you such as glowstone or torches.
Food: Caverns may have lots of intersecting tunnels making it easy to get lost or worse. Make sure you have food with you to survive.
Armor: As said before lots of mobs spawn in caverns because of low light level. Armor may be needed when exploring caverns so you have protection against mobs. Even with the difficulty on peaceful, the player can still take fall damage or fall into lava. Having armor while in lava gives you enough protection to escape from the pool. (depending on the nearest edge) And ravines and pits can be found to cause fall damage. It is recommended the player has feather falling on any kind of boots to protect against fall damage.
Other Items: You should pack a bucket of water with you in case you need to douse yourself when on fire or descend down large drops. Also bring a bucket of milk with you if you plan on entering an abandoned mine shaft, as milk can be used to heal poison from cave spiders. Multiple milk buckets may be needed. it is also worth considering bringing a stack of cobblestone or another cheap block that can be used to jump to the surface with
 Cave lakes
- Main article: Generated structures#Lakes
 Lava lakes
Most often found in large caves far underground, lava lakes are believed to have the most valuable materials near them; however, there is no proof that ores appear more around them. A lava lake can even cut through a vein of ore and reduce the amount of ore in the vein. However, if you have a bucket of water on hand, this can be a great way to obtain obsidian. Sometimes water can flow partway over them, producing a "conveyor belt to doom": Not only can the water push you into the lava, but if you die in the water, your possessions will be washed into it as well.
 Water lakes
|Pre 0.0.9a||Minecraft was first called "Cave game" in pre 0.09a on May 13, 2009. "Cave game" was renamed "Minecraft, Order of the Stone", and was later just "Minecraft."|
|0.24||Caves changed so that the deeper they are, the larger they spawn. Caves are also thinner and longer.|
|0.31||Caves are no longer filled with water as often.|
|June 16, 2010||Caves are now clustered instead of random.|
|June 17, 2010||Caves have 1-5 exits, enabling multiple escapes. Caves are now so clustered that a cave could be described as "Swiss cheese". More water and lava springs in caves. Tunnels have a wider variety of thickness. Gravel and dirt can now be found in caves.|
|1.0.3||Caves now have ambient noises such as moans and train whistles.|
|1.2.6||Pools of water and lava can now be found in caves.|
|1.2||Ores can now be found more often on the walls of caves.|
|1.4.2||12w38a||Bats added, and are the only passive mob to spawn in dark caves.|
|12w38b||New cave sounds added|
- Sand and sandstone, as well as generated structures, can overwrite caves.
- In jungle biomes, vines generate in caves near the surface.
- Though ores are abundant in caverns and often require little digging to get to, ore veins visible in the walls of the cavern often contain little ore, as the cavern cut through them when it was generated.
- Sand often will fall into caverns generated near the surface of a desert or beach and so craters in a desert will alert the player to caves below the surface.
- On 'Get Satisfaction', "rainbow crystalline caves" were marked as a planned feature by Notch.
- Hidden caves with no natural entance are very rare in Pocket Edition but the seed jpgaming produces two small dud caverns near spawn, one of which is at sea level and has some water. These can be detected with the tree glitch.