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 the 1.17 snapshot 21w15a when Mojang stated the Caves & Cliffs update would be split in two.

Planned additions

 * 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 veins of only one.
 * Can generate up to Y = 256.
 * New sub biomes Lofty Peaks, Snow Capped Peaks, Snowy Slopes, Mountain Grove, and Mountain Meadow.


 * 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).
 * 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 2 forms, cheese and spaghetti.
 * 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.

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 within the deepslate layer between -1 Y and -64 Y.
 * May contain candles.


 * 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 and influences the 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 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.