Beyond The Underground (8 New Cave Biomes!)

Version 1.7 (June 6, 2026)

New Cave Type: Arid Caves!

• Found under Savannas and Badlands.
• Lifeless terrain scattered with Petrified snags, bushes and dry grass.

New Cave Type: Crystal Caves!

• Found under Plains, Forests, Birch Forests and Taigas.
• Giant Gypsum formations and Topaz Crystals can be found here, alongside Gypsum Needles that grow from the cave ceiling.
• Home to the Crystal Firefly.

Made cave type generation more common:

• The Slimy Sewers (Slime Caves) now generate under Mangrove Swamps.
• Ice Caves now generate under all cold biomes, such as Snowy Taigas.
• The Undergrowth (Forest Caves) now generates under Flower Forests and Meadows.
• Pebbles now generate more frequently in all Overworld biomes.
• Limestone now generates in all Overworld biomes, except for Roofed Forests, Jungles, and cold & frozen biomes.
• These changes mean it’s now easier than ever to find the new caves and blocks in your world!

New Structure: Ice Fort!

• Found deep in the Ice Caves at Deepslate level. Look out for Frostslate Bricks while mining!
• Uses the Jigsaw system to procedurally generate rooms and corridors. This means every Fort you find will be unique and different from any other you’ve explored!
• Obtain special loot and crafting ingredients for the Bane of Frost.
• The legacy Ice Dungeon structure has been turned into a room in the Fort. It has a lower chance of generating than other rooms, and on average 1 will generate for each Fort. 2 mob spawners were removed for difficulty balancing, but chest contents remain the same.

Arena System Rework:

• You might not notice many changes, but most of the arena code has been refactored / rewritten to improve maintainability and scalability.
• Arenas now generate in a special room in Ice Forts, with ice-themed rewards and mob spawning.
• When interacting with an Arena Trigger in Peaceful difficulty, an error message now shows and no battle is triggered.
• The battle countdown is now visible to all players within a 32 block radius of the Arena Pillar.
• You can now start another Arena Battle immediately after one ends.
• A sound effect plays on losing.

Lost Explorer Rework:

• Their camps are now found in all parts of the Overworld between y=-50 and 20, except in Crystal Caves and the Deep Dark. (It doesn’t make sense for them to only get lost in Ice Caves!)
• They now take Topaz as currency and trade unique items from various cave types.
• They won’t sell specialties from the Crooked Caverns. The Nether is too dangerous of a travel destination!
• You no longer need an Emerald to summon the Lost Explorer.
• Unused suitcases now flash to indicate they can be interacted with.
• Removed the Ice Crystal from the Lost Explorer’s camp.

New Blocks:

• Experience Tank.
  • Deposit XP and get XP back every Minecraft day. The more you deposit, the more you get!
• Petrified Wood (Log, Wood, Planks, Slab, Stairs, Fence, Fence Gate, Door, Trapdoor). Best tool to break is a Pickaxe instead of an Axe.
• Petrified Bush
• Block of Gypsum
• Gypsum Cluster
• Gypsum Needles
• Block of Topaz
• Topaz Cluster
• Frostslate Bricks (Normal, Slab, Stairs)
• Ice Fort Lamp
• Limestone Ores (Coal, Copper, Diamond, Emerald, Gold, Iron, Lapis Lazuli, Redstone)
• Stairs (Crooked, Frosted Stone, Rainbow Gum, Slimy Deepslate Tiles, Slimy Deepslate Bricks, Slimy Stone Bricks, Limestone, Limestone Bricks, Soul Bricks, Packed Ice Bricks)

New Items:

• Gypsum Fertilizer.
  • Grows a crop or tree instantly. Put 4 Azure Bluets, Cornflowers, Dandelions, or Oxeye Daisies in a 2x2 grid to spawn a Giant Flower.
• Gypsum Shard.
  • Use to craft Gypsum Fertilizer & Combustion Amulet. Smelt to get Calcined Gypsum.
• Calcined Gypsum.
  • Put this and 8 Concrete Powder in a crafting table to get Concrete.
• Topaz.
  • Currency for trading with Lost Explorers. Use to craft Combustion Amulet and Experience Tank.
• Ice Bomb.
  • Throw at enemies to freeze them in place for 1.5 seconds.

New Special Item:

• Combustion Amulet.
  • Use to gain the Touch of Fire ability: For a specified duration, instantly smelt blocks you break and set entities you hit on fire.
  • Recharge the amulet with 1 XP level for 30 seconds in an XP Tank, for a maximum of 3 minutes.

New Mobs:

• Ice Bomber.
  • Found in the Ice Caves and Ice Forts. Throws Ice Bombs.
• Crystal Firefly.
  • Flies around leaving behind trails of topaz dust particles.

Other Changes:

• Blocks that react to redstone, such as Fence Gates and Doors, no longer rely on Minecraft:tick to detect power. This should significantly reduce tick lag, especially if you’ve placed many of these blocks.
• All blocks in this add-on now break faster when using the correct tools and tier.
• Adjusted the breaking speed by fist of some blocks to match similar blocks in vanilla.
• Some blocks now require breaking with the correct tool and tier to drop.
• Limestone variants of ores now replace the stone variants whenever ores generate in Limestone.
• Rooted Dirt patches and Hanging Roots now generate in most Overworld biomes.
• The song Excuse by C418 now plays in the Undergrowth.
• Slimy Zombies now spawn in smaller hordes.
• Thornspitters now naturally spawn in the Undergrowth.
• Luminite Ore and Deepslate Luminite Ore are now affected by Fortune.
• Sand Layers and Slime Layers are now replaceable. This means a new block (e.g. a torch) can replace them at their current position.
• Sticky Spikes and Dripping Icicles now require Silk Touch to obtain.
• You can now craft Limestone into Cobbled Limestone using a Stonecutter.
• Crooked Fungi can now be placed on Cave Turf and Deepslate Cave Turf.
• Pebbles now break when coming in contact with flowing water.
• Added explanations for some items in their item names.
• Crooked and Rainbow Gum Planks (and their products) are now in their own item groups in the creative menu.
• Used Suitcases are now available in the creative menu.
• The Slime Dagger’s special ability has been renamed as “Slimy Curse”.
• Frosted Deepslate has been renamed as Frostslate.
• Ice Dungeons no longer generate on their own.
• Instead of anvil sounds, interacting with Lava Tanks that are locked or on cooldown now plays the “block.false_permissions” sound.
• Entities can no longer jump over Beyond The Underground fences.
• Crooked Planks and Rainbow Gum Planks can now be used to craft Wooden Spears.
• Twilight Spores now generate particles less frequently to reduce lag.
• New background panorama featuring the Crystal Caves.
• Added some debug commands. These aren’t meant for general use. Use them at your own risk.
• This add-on now requires Minecraft 26.20 or above to function.

Fixed Bugs:

• All Beyond The Underground hostile mobs now only spawn at a light level of 0.
• Lava Tanks now work again.
• Water no longer flows through non-full blocks.
• Texture flickering no longer occurs on blocks with cross-shape geometries.
• Fixed “Invalid asset path” errors that appeared in the content log.
• Fixed the high spawn weights of mobs that prevented other mobs from spawning.
• Crooked Stems can now be stripped.
• Crooked wood now play nether wood sounds.
• Limestone Slabs, Rainbow Gum Slabs and Slimy Deepslate Brick Slabs now play the correct sounds.
• Luminous Mushroom Stew, Mysterious Stew, Slime Soup and Crooked Fungus Stew are now available in the creative menu.
• You can now craft campfires using Crooked and Rainbow Gum Logs / Wood.
• Fixed incorrect map color for Rainbow Gum Planks.
• The Bane of Frost now breaks Chiseled Packed Ice faster.
• Fixed incorrect information in some loading screen tips.
• “Can’t find animation…” errors no longer appear when encountering a Slimy Zombie.
• Content log errors no longer appear when breaking blocks at y=1 or y=319.
• Content log errors no longer appear saying Beyond The Underground spawn eggs were put into the wrong category.
• Fixed “minecraft:render_offsets has been deprecated…” content error upon world load.
• Undead mobs are now immune to Soul Magma Blocks.