Cave



Caverns 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 no two of them will look exactly alike, making guides hard to be formed. 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 so it is advisable to bring along a weapon if on any difficulty other than peaceful. 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.

Pits
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 near bedrock.

Finding Caverns
There are a number of ways to find caverns. Below is a table, designed to make cavern-hunting easier.

Navigating Caverns
It is surprisingly easy to get lost in caverns. Below are a number of methods you can implement while exploring to prevent this.


 * Place all your torches on the right side of the cave when you enter a new passage. This allows you to find you way back to the entrance simply by keeping the torches on your left. When encountering multiple caverns, also known as a fork, put two torches at the exit to indicate the correct way to exit the cavern. However, be aware that if a cave loops back on itself at some point, there can be some confusion as to the shortest way out. Also, it is unlikely that torches restricted to the right side will provide sufficient light to completely prevent mobs from spawning, so you will probably need to place additional torches on the cavern floor in caves and the wider passageways.
 * Use signs to create directional signposts at intersections, often with "ASCII arrows", such as --> or ^, to indicate the heading. Keep in mind that you will need to be able to see these signposts the most on your way back out of the cavern, so when placing them, it is important to position them where they will be easily visible from the other direction. While this method is generally very reliable, signs are not cheap (6 wooden planks and 1 stick per sign), nor do they stack, making it difficult to bring enough signs for anything larger than a medium-sized cavern system. However, you can bring stacks of planks and sticks, which do stack.
 * Create cobblestone arrows at each intersection, pointing back towards the passage you just came from. A torch can be placed on the block at the tip of the arrow to ensure that the arrow is easy to spot. This method has the advantage of utilizing a resource (cobblestone) that is common in caverns and easily carried in bulk, making it suitable for aiding in the exploration of even the most massive caverns. These arrows can be placed on walls or embedded into the floor, and can point in any direction. Similarly to the signpost method, cobblestone arrows should be placed in locations that are easily visible on the way back out of the cavern.
 * Similarly, a player can make cobblestone walls or barricades to block off dead-ends or previously explored cavern branches to find exits more quickly. This along with the "right-side" torch method work very well hand-in-hand and can guarantee a less confusing exit strategy for players in a hurry to end their cavern run.
 * When finished exploring a cave, simply dig upwards to the surface in a staircase fashion, keeping in mind not to dig the block just above you.
 * If a player does not use redstone and merely ignores it or collects it, they can make simple "trails" from spare redstone dust to either illuminate (if the player wishes to use sticks and make torches) or help the player find a set path out of the cave, much like a Hansel and Gretel style of approach to spelunking. (Note, this should only be used if the player is willing to sacrifice their redstone dust or torches and should be only be used if the player has a general idea of where exactly their exit is.) Alternatively, this can also be done with minecart tracks if the player wishes.
 * You can also use redstone torches by placing them regularly within sight of each other, they are very easy to see and you can easily follow the torches back to where you first started placing them.
 * The alternative is to use characteristic blocks to mark your way by placing them regularly. If you made a portal, netherrack is recommended, while it is very quick to mine, and not naturally occurring in the Overworld. When going back, you can simply burn them, recovering torches and marking explored paths.
 * 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. Since it maps ~250 blocks in each direction from where it is crafted, crafting it at the cave entrance can be a useful way to gain your bearings, especially since most caves occupy less area horizontally than they might seem.
 * An important tip to remember in caves is to: Always Look Up! One of the most common sources of mobs within previously explored caves is unnoticed openings in the ceiling.

Classification of Caverns
A cavern can be classified into the following kinds of cave systems.

Small Cave (Dud Cave)


Small caves 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 caves 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 (Epic Cave)


Epic 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 epic caverns is often rather hard, due to the huge volume of naturally generated tunnels often part of epic caverns. It is not uncommon for dungeons to be found within these systems.

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. Although not particularly of interest, from a mining perspective, they may appear unnatural and irregular in regards to the surrounding terrain. Very rarely, a dungeon can be found in these rooms.

Ravine


Natural formations of stone and gravel that can cross a big part of an island. It's a bit 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 water fall. 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.

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.

An example of a deep chasm (generated before the Beta 1.8 update) can be seen at about seven minutes in this video: Far Lands or Bust #67

Giant Entrance


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.

Lava lakes


Most often found in Large Caves far underground, Lava lakes generally have the most rare minerals including Lapis Lazuli, gold ore, and redstone ore, sometimes even diamond ore. But Lava Lakes most often hold the common minerals such as iron ore and Coal. If you have a bucket of water on hand, this can be a great way to obtain obsidian. Lava lakes are always found on layer 10 and below, as the map generation still creates caves below this layer, but lava will fill up any air beneath here.



Water lakes


Found in every part of the world at every level underground, Water lakes are by far the most common lake. Water lakes occur on the surface, a mere 1-20 blocks below the surface, and from then on to Bedrock.

History
As of the 12w05a snapshot, lava makes a sound as well.

Trivia

 * Sand and sandstone overwrite caves.
 * There are currently seven different types of caves.

Bugs

 * Caves and Ravines did not generate in the Overworld in 12w07a and 12w07b.
 * Vines currently generate in caves near the surface in jungle biomes, it is unknown if this was intended or not.