ZMJJKK123-hub Caves & Cliffs Prototype Data Pack
A Mojang-published data pack (like Bedrock's experimental gameplay), first shipped with snapshot 21w15a (April 14, 2021), letting players experience the worldgen changes between 21w06a and 21w14a before 1.18 development.
Version 1 (21w15a)
- Noise caves: spaghetti caves (long/curved, sometimes wide like tagliatelle) and cheese caves (Swiss-cheese-like holes of varying sizes); noise-generator based; entrances form where caves meet the surface.
- Aquifers: replace old underwater carver caves and canyons; generate water bodies in noise caves (below Y=31); magma blocks on aquifer floors create whirlpool bubble columns; fish spawn in aquifers under oceans/rivers.
- Cracks (fissures): narrower/straighter than canyons, extending from the surface up to 90 blocks deep into deepslate.
- World height: buildable range now −64..319 (384 total).
- Ore changes: most ores gained spread-type generation (like lapis); some kept linear too. Coal: spread Y0–192 (peak 96) + linear Y136–319; copper: linear Y0–63; diamond: spread Y−144..16 (peak −64) + separate large clusters; emerald: spread Y32–480 (peak 256); gold: spread Y−64..32 (peak −16; badlands unchanged); iron: linear Y−64..−32 + spread Y−24..56 (peak 16) + spread Y128–384 (peak 256); lapis: spread Y−32..32 (peak 0) + linear Y−64..64 (buried like ancient debris); redstone: spread Y−96..−32 (peak −64) + linear Y−64..15. Frequency changes: less exposed coal, less copper, smaller/more frequent diamond blobs (50% not air-exposed), more emerald, more gold (50% not exposed), less iron, more buried lapis, less redstone. Deep variants generate when replacing deepslate/tuff (coal/copper/emerald never below Y=0 → no deep variants).
- Deepslate: primary rock below Y=0; stone→deepslate transition Y=−1..−8, full below −8; tuff randomly replaces deepslate there; still clusters at Y0–16.
- Diorite/andesite/granite: larger, rounder, rarer clusters; never below Y=0.
- Dirt never below Y=0; tuff clusters below Y=0; lava starts at Y=−54; strongholds fully wrapped in deepslate.
Version 2 (21w16a)
Rare snaking ore veins: large copper veins with granite above Y=0; large iron veins with tuff below Y=0. Aquifers below Y=0 can be fully lava.
Version 3 (21w17a)
Noodle caves (narrower, more winding, tighter than spaghetti). Veins rarer/smaller, ore unevenly distributed with more clustering, may contain raw iron/copper blocks. Emerald now replaces granite/diorite/andesite/tuff/deepslate; coal/copper can replace deepslate/tuff at Y0–16 (deep variants).
Version 4 (21w18a)
Slightly less copper; medium iron clusters rarer; small iron cluster max height −32 → 64. Veins smaller/rarer with more raw metal blocks. Carver caves now generate under oceans below Y=0; noodle caves no longer above Y=30; larger minimum sizes for carvers and noodles. Deepslate no longer clusters above Y=0 (deep coal/copper gone again).
Version 5 (21w19a)
Bundle and candle crafting recipes added.
Version 6 (21w20a)
No listed changes.
Version 7 (1.17-pre1)
Candle crafting recipe removed.
Version 8 (1.17-pre2)
For 1.17-pre2+; no listed changes.
Trivia
The pack adds no new worldgen mechanisms — it simply enables mechanisms already present in the client.jar since 21w15a but inactive in vanilla.