Marvellous mountains and colossal caves, this snapshot has it all! Today we're bringing the Overworld revamp to regular snapshots. If you've been playing or checking out the experimental snapshots that we've been releasing, you should be familiar with what you're seeing. If not, you're in for a treat!

Since we're extending the world height, and there are quite a few under-the-hood changes, we've been keeping an eye on how the game is running, and there are still improvements to be made. However, we would still appreciate it if you would be able to take this survey so that we can understand how you perceive the performance of this snapshot.

It should also be noted that there is currently no upgrade path for existing worlds in this snapshot. This means that you can only create new worlds in this snapshot, and not play on any of your existing worlds. We're working on this and you should be able to play on your existing worlds in an upcoming snapshot not too far in the future.

All of this said, we hope that you have a great time checking out these new additions. Watch your feet so that you don't fall into a very deep hole, and make sure you don't get punted off a mountain by a goat that's just minding its own business.

Happy mining!

New Features in 21w37a

Added noise caves and aquifers
Added Dripstone Caves underground biome
Added Grove biome
Added Lofty peaks biome
Added Lush Caves underground biome
Added Meadow biome
Added Snowcapped peaks biome
Added Snowy slopes biome
Added Stony peaks biome
New ore distribution and large ore veins
Overworld build and generation limits have been expanded

Blocks

Enchanting Tables now emit a low amount of light
Using shears on the tip of a Cave Vine, Twisting Vine, Weeping Wine or Kelp now causes it to stop growing

Dripstone Caves biome

Contains plenty of Pointed Dripstone and Dripstone Block on the floors and ceilings, and small pools of water
In some places you'll find larger stalagmites, stalactites, and columns built from Dripstone Blocks
Contains extra copper ore

Grove

Snowy terrain with big spruce trees and powder snow traps. Might want to wear leather boots!
Tends to generate on high-altitude terrain beneath mountain peaks or on hilltops.
Spawns wolfs, rabbits, and foxes.

Large ore veins

Ore veins are large, rare, snake-like underground ore formations
Copper veins form between y 0 and y 50 and are mixed with Granite
Iron veins form below y -60 and y -8 and are mixed with Tuff

Lofty peaks

Dramatic jagged mountain peaks with snow and stone
Spawns goats

Lush Caves biome

Moss covers the floors and ceilings
Spore Blossoms grow from the ceiling and drip particles
Contains Clay pools with Dripleaf plants growing out of them
Contains Azalea Bushes and Flowering Azalea Bushes
The Azalea Tree loves to have its roots in Lush Caves, so if you find an Azalea Tree (either overground or in a cave) you know there is a Lush Cave beneath you
Cave Vines with Glow Berries grow from the ceiling and light up the caves

Meadow biome

Large grassy and flowery biome that tends to generate high up on plateaus or next to large mountain ranges.
Sometimes contains a lone tall oak or birch tree, often with a bee nest.
Think Sound of Music!
Spawns donkeys, rabbits, and sheep.

Mob Spawning

Monsters now only spawn in places where the light from blocks is 0 (sky light still prevents spawning like before)
Fixed an issue where players in multiplayer can face more or far fewer enemies than intended, particularly when other players are flying

New ore distribution

Changed ore generation to match the new world height, and to add more strategy to mining.
There is no longer a single y level that is best for all ores, you need to make tradeoffs.
Iron ore generates below y 72, with a strong bias towards y 16.
Iron ore also generates above 112, with more iron ore as you go higher.
Copper ore generates between y 0 and y 96, with a strong bias towards y 48.
Copper ore generates in larger amounts in dripstone caves biome.
Lapis lazuli generates below y 64, with a strong bias towards y 0. However, Lapis below y -32 or above y 32 cannot generate exposed to air. It will either be buried or inside water.
Coal generates above y 0, with a strong bias towards y 96 and above.
Coal has reduced air exposure, so you will find more coal buried or underwater than exposed to air.
Gold generates below y 32, with a strong bias towards y -16.
Extra gold can (still) be found in badlands biomes.
Redstone ore generates below y 16. Redstone ore generation gradually increases as you go below y -32 and further down.
Diamond generates below y 16, with more diamond the lower you go.
Diamonds have reduced air exposure, so you will find more diamond buried or underwater than exposed to air.

Noise caves and Aquifers

Noise caves are a new way of generating caves, providing more natural variety. They can get really huge sometimes! Noise caves come in three flavors:
- Cheese caves. Like the holes in swiss cheese. These often form caverns of various size
- Spaghetti caves. Long squiggly tunnels, sometimes wide like tagliatelle
- Noodle caves. Thinner, squigglier, and more claustrophobic variant of spaghetti caves
No, they aren't loud. The "noise" part of noise caves is a technical term and has nothing to do with sound
The old cave carvers and canyons still generate, combining with the noise caves to form interesting cave systems
As with carvers, when noise caves intersect the surface they form cave entrances
An aquifer is an area with local water level, independent of sea level. Aquifers are used during world generation to generate bodies of water inside noise caves. This sometimes results in large underground lakes! They can also form inside mountains and on the surface.
Aquifers below y0 will sometimes be lava aquifers instead of water aquifers
Magma Blocks sometimes generates at the bottom of underground bodies of water
Underwater cave carvers and underwater canyons have been removed, since aquifers are used to generate water in caves instead

Options

Added an accessibility option to stop the sky flashing during thunderstorms
Added an option to specify the audio device used by the game
Added "Toggle Sprint" and "Toggle Sneak" to the Controls settings
Moved Keybinds out to their own settings screen, accessible from Controls

Snowcapped peaks

Smooth mountain peaks with ice and snow
Spawns goats and yeti. No actually just goats.

Snowy slopes

Very snowy terrain that can hide powder snow traps. Might want to wear leather boots!
Tends to generate on high-altitude terrain beneath mountain peaks or on hilltops.
Spawns rabbits and goats.

Stony peaks

Stony mountain peaks that may be jagged or smooth
Spawns goats
Contains strips of calcite sometimes

World generation

Generation range and build limits have been expanded by 64 blocks up and 64 blocks down, to a total range of 384 blocks
Underground features, structures, and caves generate all the way down to y-64
Exception: Diorite and Granite and Andesite and Dirt don't generate below y0
Tweaked size and positioning of Diorite, Andesite & Granite generation
Dripstone clusters can no longer be found in normal caves, only in dripstone caves biome
Starting from y0 and below deepslate gradually replaces all stone
Deepslate blobs no longer generate above y0
The terrain shape and elevation varies dramatically, indepedently from biomes. For example, forests and deserts could form up on a hill without needing a special biome just for that
Less diorite/granite/andesite generates above y 60
Strips of gravel can generate in stony shores
Swamp trees can grow in water 2 blocks deep (instead of just 1 block deep)

Changes in 21w37a

Illagers (Vindicator, Pillager, Evoker) no longer attack baby villagers
Axolotls now only spawn in lush caves
Axolotls now have their own, separate, mob cap
Raised the cloud level from 128 to 192

Technical Changes in 21w37a

Replaced the clientbound chunk update network packet with another one which additionally contains light update data. Separate light update packet still exists and is sent when light update happens without chunk update.
View distance now causes chunks to load cylindrically around players instead of in a square
Information about the world generation noise is now displayed on the debug screen
Added illageralt, rune-like font from Minecraft Dungeons (currently only usable via commands)
Added startup option --jfrProfile and command jfr to start profiling with Java FlightRecorder as well as a few custom events.
Loot table functions set_contents and set_loot_table now require type field with valid block entity type
Worlds last saved before Minecraft 1.2 ("pre-anvil") no longer can be opened directly
Data pack format has been increased to 8
New video setting "Priority updates".
Removed length limits for scoreboard, score holder and team names
Mob spawners can now override light checks for spawning

JFR Profiling

Custom events

minecraft.ServerTickTime: sampling event exposing average server tick times at one second intervals
minecraft.ChunkGeneration: time taken to generate individual chunk stages
minecraft.PacketRead | minecraft.PacketSent: network traffic
minecraft.WorldLoadFinishedEvent: initial world loading duration

Ending a profiling run

The run will then be stopped either by:

shutting down the JVM
jfr stop in-game command
jcmd CLI tool

Overview

Java Flight Recorder (https://openjdk.java.net/jeps/328) is the internal JVM profiling tool bundled with the Java Runtime to analyze performance and runtime characteristics. It's a useful tool for exposing internal JVM performance metrics as well as custom metrics that can be monitored or analyzed using any stock Java profiler or monitoring agents.

Reports

A summary JSON report is written both to the log file and in the debug folder accompanied by a .jfr recording ready to be analyzed in i.e JMC https://github.com/openjdk/jmc or any other profiler tool supporting the format.

Starting a profiling run

A profiling run can be started using any of the following alternatives:

--jfrProfile startup flag when starting a Minecraft server or client
jfr start in-game command
Regular Java CLI tools such as jcmd

Loot tables

Changed functions

`set_contents`, `set_loot_table`

Added new mandatory field type. This type will be written into BlockEntityTag.id, to make sure this tag can be correctly migrated between versions

Old world conversion

Worlds last saved before Minecraft 1.2 ("pre-anvil") now require conversion in a previous version of a game to be able to be opened
Conversion works best in versions 1.6.4 and before - worlds opened for the first time in later versions will have incorrect biome information

Priority update setting

This setting determines which chunks sections are updated synchronously during a single frame.
The most conservative option "nearby" corresponds to the state before the update.
The new options "by player" and "none" significantly reduce stutters when placing or removing blocks (especially light sources), but can potentially cause rare visually noticeable delays in world updates.

Spawner data changes

Spawners now support the custom_spawn_rules NBT in the SpawnData field and the SpawnPotentials list
custom_spawn_rules currently may contain fields block_light_limit and sky_light_limit - both are integer ranges with fields min_inclusive and max_inclusive
To make SpawnPotentials format similar to other weighted lists, structure was changed to {weight: <int>, data: <previous contents without 'Weight', 'Entity' renamed to 'entity'>}
To accomodate that change, previous contents of SpawnData were moved to SpawnData.entity (making format of that field same as elements of SpawnPotentials.data)

Example:

SpawnData: {
    entity: {
        id: "minecraft:cow"
    },
    custom_spawn_rules: {
          sky_light_limit: {min_inclusive: 10, max_inclusive: 15}
    },
}
SpawnPotentials: [
  {
    data: {
      custom_spawn_rules: {
          block_light_limit: {min_inclusive: 0, max_inclusive: 15}
      },
      entity: {id: "minecraft:pig"},
    },
    weight: 2
  },
  {
    data: {
      custom_spawn_rules: {
          block_light_limit: {min_inclusive: 5, max_inclusive: 10},
          sky_light_limit: {min_inclusive: 10, max_inclusive: 15}
      },
      entity: {id: "minecraft:panda"}
    },
    weight: 1
  }
]

Fixed bugs in 21w37a

MC-29274 Withers will not pursue players in survival mode unless attacked
MC-30560 River through Eroded Badlands biome generates floating rock formations at water surface
MC-54545 Client render distance doesn't adjust to server render distance if they are different, causing faulty chunk loading
MC-65628 Desert pyramids generate underground when using amplified or custom terrain
MC-123277 Too long scoreboard objectives and team names are not detected when commands are parsed
MC-129266 Jagged ocean transitions and slower biome generation
MC-138801 The interactions between a biome and another biome and its variants are inconsistent
MC-140690 Giant Spruce Taiga Hills has no difference with Giant Spruce Taiga
MC-159025 Drowned do not spawn in warm ocean biomes
MC-160710 Chat messages written while sleeping are deleted after waking up
MC-166423 Splash water bottles don't damage endermen
MC-182362 Score callbacks with a too long name break callback chain
MC-202376 Rabbits, instead of spawning on snow blocks, spawn on snow layers
MC-208601 Axolotls do not avoid danger when pathfinding
MC-212113 Glow Lichen can spawn underwater whilst not in a cave.
MC-213779 FPS drops when looking up in a tall world (4064 blocks)
MC-214783 Oceans generate with stone floors
MC-214797 Pointed dripstone can generate floating at transitions between local water levels
MC-214799 Aquifiers sometimes create air pockets
MC-214864 Hard edges when new caves generate near surface
MC-214989 Isolated floating mineshaft platform
MC-215296 Mineshafts often don't generate in floating island worlds
MC-215876 Dirt can generate below y=0 from mineshafts
MC-216784 Ruined Portals don't generate below y=0
MC-216952 Some chunks interrupting with cave systems filled with blocks
MC-216967 Kelp & Seagrass can generate in aquifers
MC-217465 Unnatural shape looking like a chunk border but appears to be completely unrelated to chunk borders
MC-217509 Inefficient generation of aquifers, noise caves and ore veins
MC-219774 Magma blocks generate everywhere underwater in 21w10a
MC-219946 Weird flat sections of terrain
MC-221777 Horses donkeys, mules, llamas, and trader llamas do not follow players holding food
MC-221815 Flat roofs in underwater caves
MC-221917 Dripstone, pointed dripstone, and cave magma generate in oceans
MC-222051 Iron Ore generation was not increased in 21w13a
MC-222379 Magma can spawn under air in underwater caves
MC-223044 Floating Water can generate in ravines
MC-223051 Dripstone can generate in surface lakes
MC-223148 Extended height message goes behind the scrolling bar
MC-226184 Axolotls pathfinding to water can sometimes fall in wide holes
MC-227244 Ore blocks from ore veins float in underwater magma ravines
MC-230343 Parity issue: enchanting tables do not emit a light level of 7
MC-231721 Dinnerbone Animals do not look at food correctly.
MC-231863 Game crashes when trying to access the realms settings

Minecraft Snapshot 21w37a