Java Edition 1.18

1.17, the second release of Caves & Cliffs, is an upcoming major update to  set to release in late 2021. It was first announced alongside the release of 1.17 snapshot 21w15a when Mojang stated the Caves & Cliffs update would be split in two. Features from 1.18 are being developed alongside 1.17, and an official data pack has been released by Mojang to preview the world generation changes.

Blocks

 * Will generate in the mysterious new cave biome, referred to as the "deep dark".
 * Has an animated texture.
 * May be used in redstone.
 * May be used in redstone.


 * Will generate in the deep dark biome.
 * Has a different top texture than the Sculk Block and Sculk Chute.
 * May be used in redstone.
 * May be used in redstone.


 * Will generate in the deep dark biome.
 * Made of sculk and a bone-like material.
 * May be used in redstone.
 * Glows but does not emit light, similar to the glow squid or the glow item frame.
 * Glows but does not emit light, similar to the glow squid or the glow item frame.


 * Will generate in the deep dark biome.
 * Generates in a layer on top of blocks, similar to snow.
 * Can be placed in all directions, like glow lichen.
 * Some have parts that are transparent, allowing the player to see the block it is on top of.
 * May be used in redstone as seen in this video when they talk about the sculk sensor.
 * May be used in redstone as seen in this video when they talk about the sculk sensor.

Items

 * Warden Spawn Egg.png Warden spawn egg.
 * Warden Spawn Egg.png Warden spawn egg.

Mobs

 * Will spawn in the new deep dark cave biome.
 * The first fully blind mob (bats, despite relying almost exclusively on echolocation, still have basic eyesight).
 * When sensing movement, it moves toward the source of the movement.
 * It follows and attacks players, mobs, and other entities that make vibrations.
 * It does not attack other Wardens.
 * When attacked, it path finds toward the player.
 * Seems to follow the same rules as the sculk sensor when detecting noise.
 * When it detects a vibration, the growths on its head rattle and light up, similar to the sculk sensor.
 * If any projectile (e.g. egg, snowball, arrow) lands near the Warden, the mob inspects the location where the projectile landed, due to the projectile creating movement and noise. This feature can be used in order to cause a distraction.
 * Does not detect players that are sneaking.
 * Can detect players that are invisible.
 * When aggravated for long enough, the warden follows the player continuously, regardless of any other distractions.
 * Incredibly strong, doing damage, bringing players wearing full netherite armor from full health to  health points.
 * A mob designed to be extremely difficult and fled from.
 * Has a way to counter the strategy of building up 3 blocks to avoid attacks.
 * At least as fast as the player's walking speed.
 * Seems to have knockback resistance.
 * The warden's chest has a glowing core that appears to brighten and dim in tandem with the ambient lighting of the deep dark cave biome.
 * The core creates a low throbbing sound as it pulses. The sound and animation seem to speed up rapidly when the warden notices a player.
 * Is about 3.5 blocks tall, making it one of the tallest mobs in the game, exceeding the iron golem and enderman in height and width (the same).
 * Is about 3.5 blocks tall, making it one of the tallest mobs in the game, exceeding the iron golem and enderman in height and width (the same).

World generation

 * Mountains


 * Height dependent generation.
 * Revamped, featuring some new small spruce trees on the slopes and ice and packed ice above the peaks.
 * Contain goats, rabbits, snow blocks, snow layers and powder snow.
 * Iron ore, emerald ore and coal ore are found in abundance.
 * Emerald ore no longer generates in blobs of only one.
 * Can generate up to Y=256.
 * New sub biomes.


 * Caves


 * Completely overhauled.
 * Now stretch down to Y=-59.
 * The cavern now generates in 2 layers of different stone bases depending on the depth.
 * Cavern layer above Y = 0 is made up of regular stone.
 * Stone transitions to deepslate from Y=0 to Y=-7.
 * Deepslate now completely replaces stone from Y=-8 to bedrock.
 * Certain types of ores and structures still generate in the deepslate layer, as well as tuff.
 * Dirt, diorite, granite and andesite do not generate in this layer.
 * Biomes inside of caves introduced such as dripstone caves.
 * Contain aquifers, bodies of water with different heights, independent of sea level (Y=63).
 * Aquifers below Y=0 sometimes generate with lava instead of water.
 * Improved old caves to blend in with the new generations of caves better.
 * New carver called crack carver, which appears as a fissure on the ground, like ravines but narrower and can go very deep.
 * New noise caves, coming in 3 forms, cheese, spaghetti and noodle.
 * The original caves still exist, mixing with the noise caves.
 * Cheese caves have large stone towers stretching from the bottom of the cave to the top.
 * Very large, often large enough to fly with an elytra.
 * Abundant with aquifers and ores.
 * Spaghetti caves are long, thin caves that have small aquifers and are more similar to original caves.
 * Noodle caves are thinner, squigglier and more claustrophobic variants of spaghetti caves.


 * Ore veins
 * Large, rare, snake-like ore formations.
 * Copper ore veins mixed with granite generate above Y=0.
 * Iron ore veins mixed with tuff generate below Y=0.

Biomes

 * Deep Dark biome


 * New biome at the "deepest depths of the world".
 * Wardens can spawn here.
 * Contains sculk blocks and sculk sensors.
 * Contains deepslate.
 * Likely generates exclusively within the deepslate layer between Y=-1 and Y=-64.
 * May contain candles.


 * Dripstone Caves




 * Contains pointed dripstone (both stalactites and stalagmites) and dripstone blocks.
 * Dripstone clusters are abundant here, often forming pillars.


 * Lush Caves




 * Contain moss, moss carpet, spore blossom, glow berry vines, big dripleaf and small dripleaf.
 * Moss covers the ceilings and floors.
 * Axolotls can spawn here.
 * Clay pools generate inside.


 * Mountains


 * Come in 5 sub-biomes:
 * Mountain Meadow
 * The lowest layer of a mountain.
 * Contain flowers and sweet berry bushes.
 * Mountain Grove
 * The second lowest layer of a mountain.
 * Covered in snow, snow blocks and powder snow, and is filled with spruce trees.
 * Rabbits spawn in this biome.
 * Snowy Slopes
 * The second highest layer of a mountain.
 * Covered in snow, snow blocks, powder snow and ice.
 * Goats spawn only in this biome.
 * Lofty Peaks
 * The highest layer of a mountain, and will only generate if the mountain is high enough.
 * Generates if the surrounding biomes are too warm for snow capped peaks.
 * Covered in snow and ice.
 * Snow Capped Peaks
 * The highest layer of a mountain, and will only generate if the mountain is high enough.
 * Generates if the surrounding biomes are too cold for lofty peaks.
 * Covered in snow, snow blocks, powder snow, ice and packed ice.

Gameplay



 * While in the deep dark cave biome, the ambient lighting occasionally dims temporarily, limiting the player's visibility. This serves as a warning that the warden is nearby.

World generation

 * More extreme and smooth terrain.
 * Likely change to the generation of alternate stone types, to make them appear in larger but less numerous deposits.
 * Possibly seen in a screenshot tweeted by Henrik Kniberg, in which diorite appears to generate in a long and flat horizontal strip, rather than a small unevenly shaped patch.
 * Ore generation has further rebalancing to add strategy to mining.
 * This is also largely through the addition of ore veins, which influence surrounding stone.Caves & Cliffs approximate ore distribution - third iteration.jpg.jpg.]]


 * Fossils


 * The fossils in the deepest part of the underground generate with Deepslate Diamond Ore instead of Coal Ore.


 * Strongholds


 * Try to generate fully encased in stone, or deepslate at low y-levels.

Structures

 * Underground Cabin


 * Seen in the Deep Dark biome during the Minecraft Live 2020 stream.
 * Consists of a chamber with a cobblestone floor and stripped log support beams, containing 3 barrels, a blast furnace, and a large chest, with cobwebs and candles in and around it.
 * May possibly not be a generated structure, but instead a construction built for the purpose of the Warden showcase.

Trivia

 * This is the first major update for Java Edition that is split into two updates since Adventure Update in 2011.