Java Edition 1.18

1.18, 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 that the Caves & Cliffs update would be split in two. Features from 1.18 were developed alongside 1.17, previewed in official data packs used with a corresponding 1.17 snapshot.

World generation

 * 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.
 * Dripstone Caves and Lush Caves now generate naturally underground.
 * 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 with their generation slightly tweaked to better blend in with 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 springs, 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.


 * Mountains
 * Come in 5 sub-biomes:
 * Meadow
 * The lowest layer of a mountain that look like a flowery and colder plains, with an aqua grass color.
 * Contains grass, tall grass, dandelions, azure bluets, cornflowers poppies, daisies, alliums, and dead bushes.
 * Unlike the, it does not contain sweet berry bushes.
 * Only rabbits, donkeys and sheep spawn in this biome.
 * Grove
 * Reminiscent of a snowy taiga with snow blocks instead of grass blocks.
 * The second lowest layer of a mountain.
 * Covered in snow, snow blocks, powder snow and is filled with spruce trees.
 * Rabbits, wolfs, foxes, sheep, pigs, chickens and cows spawn in this biome.
 * Snowy Slopes
 * The second highest layer of a mountain.
 * Covered in snow, snow blocks, powder snow and ice.
 * Only rabbits and goats spawn in this biome.
 * Lofty Peaks
 * The highest layer of a mountain which will only generate if the mountain is high enough.
 * Generates if the surrounding biomes are too warm for snow capped peaks.
 * Covered in snow, snow blocks and ice.
 * Only goatss spawn in this biome.
 * Snowcapped Peaks
 * The highest layer of a mountain which 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, ice, and packed ice.
 * Only goats spawn in this biome.


 * Ore veins
 * Long and rare ore formations.
 * Copper ore veins mixed with granite and raw copper block generate above Y=0.
 * Iron ore veins mixed with tuff and raw iron block generate below Y=0.

Technical

 * Debug screen
 * Added two new lines: Multinoise and Terrain.
 * Only appear if the dimension where the player is uses the multi-noise biome source type.
 * Multinoise lists the parameters used at the player's position in order to place a biome. C is continentalness, E is erosion, T is temperature, H is humidity and W is weirdness.
 * Terrain lists values related to terrain generation.

General

 * Tags
 * Spawners now have a new tag, which lets players override the spawn rules of the spawned mob.
 * In the tag, players can specify, which indicates the highest block-light the spawners will spawn mobs at.

Blocks

 * Sculk Sensor
 * Have been re-added to the Creative Mode inventory.

Items

 * Bundle
 * Have been re-added to the Creative Mode inventory.
 * Can once again be crafted.

Mobs

 * Axolotls
 * Now only spawn in lush caves.
 * Goat
 * Now only spawn in snowy slopes, lofty peaks, and snowcapped peaks biomes.
 * General
 * Hostile mobs will only spawn in areas where the light level is equal 0.
 * This change only affects block-light and not sky-light.
 * Zombie, skeleton, spider, and cave spider spawners now spawn mobs up to block-light level 11.

World generation

 * Overworld
 * Now uses the multi-noise biome source type.


 * Lush Caves and Dripstone Caves
 * Now generate naturally underground and inside hills or mountains.
 * Azalea trees now generate above lush caves.


 * Deep Warm Ocean
 * Now generates naturally.


 * Beaches
 * Beaches are generally wider.
 * In some places there is a chance where no beaches generate at all, to provide some variation.


 * Extreme Hills
 * Renamed mountains to extreme hills, and gravelly mountains to gravelly hills.


 * Sub-biomes
 * Wooded hills, birch forest hills, tall birch hills, taiga hills, taiga mountains, gravelly mountains+, desert hills, desert lakes, shattered savanna plateau, swamp hills, dark forest hills, snowy mountains, snowy taiga hills, snowy taiga mountains, modified jungle, jungle hills, bamboo jungle hills, jungle edge, modified jungle edge, giant tree taiga hills, giant spruce taiga hills, badlands plateau, modified badlands plateau, modified wooded badlands plateau, and mushroom field shore biomes no longer generate naturally.
 * Whether any of the biomes listed will be re-added is currently unknown.


 * General
 * Terrain generation is now independent from biomes, with biomes adapting to whatever terrain they happen to generate throughout.
 * This allows for natural variation in the terrain of any individual biome, both in terms of shape and elevation.
 * For example, forests and deserts could form up on a hill without needing a special biome just for that purpose.
 * This additionally allows for smoother transitions between biomes.
 * Terrain is now smoother and more extreme.

General

 * Height limit
 * Has been increased to 384 blocks, expanding 64 blocks up and 64 blocks down, with 320 being the limit upward and -64 being the limit downward.


 * Clouds
 * Raised cloud level from 128 to 192.


 * World types
 * Removed the Large Biomes and Amplified world types.

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

 * Goat Horn
 * Dropped by a goat if it rams into a block.
 * When used for a short period of time, it makes a sound identical to the horn heard during raids.


 * 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.
 * Will burn in direct daylight.
 * Incredibly strong, doing damage, bringing players wearing full netherite armor from full health to  health points.
 * It is the only mob that spawns in the Deep Dark.
 * Does not spawn like normal hostile mobs, but instead uses completely new spawning rules.
 * A mob designed to be extremely difficult, intended to be 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).

Biomes

 * Deep Dark
 * New biome at the "deepest depths of the world".
 * Wardens can spawn here.
 * Contains sculk blocks and sculk sensors.
 * Contains deepslate.
 * Generates exclusively within the deepslate layer between Y=-1 and Y=-64.
 * May contain candles.
 * May contain loot chests.
 * With the exception of spawners, no other mobs can spawn here, similar to mushroom fields.

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.
 * 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.

Mobs

 * General
 * Hostile mobs will only spawn in areas where the light level is equal 0.
 * This change only affects block-light and not sky-light.

World generation

 * 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.


 * 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.


 * General
 * Terrain generation is now independent from biomes, with biomes adapting to whatever terrain they happen to generate throughout.
 * This allows for natural variation in the terrain of any individual biome, both in terms of shape and elevation.
 * For example, forests and deserts could form up on a hill without needing a special biome just for that purpose.
 * This additionally allows for smoother transitions between biomes.
 * Terrain is now smoother and more extreme.

World generation



 * Other Stones
 * Diorite or calcite and what appears to be tuff spawn in layers of stone in straight lines instead of splotches.

Blocks



 * Spore Blossom
 * Can close.


 * Azalea Log
 * Between Java Edition snapshots 21w05a and 21w10a, many blocks (flowers, leaves, grass, ferns, sweet berry bushes, small dripleafs) had a block tag called "azalea_log_replaceable", possibly implying the existence of azalea logs.

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.
 * This is also the first major update that starts with "experimental" snapshots, instead of regular snapshots.