Cavern Calamity Add-on 1.21+

The depths of the Minecraft world hide much more than just stone and ore. Every experienced crafter knows this. If standard caves have become boring, the mod Cavern Calamity will make them frightening and exciting once again. 11 new biomes, unique materials, weaponry, and even creepy bosses — now every archaeological adventure will be a real challenge.

Jasper Caves

You can find a new variant of Amethyst — Jasper

Kyanite Caves

Kyanite is also a type of amethyst, but it's blue

Amethyst Caves

Calcite also generates

Slimy Sewers

Lots of Slime

Glowing Mushroom Caves

Peaceful cave

Glittering Lush Caves

Many beautiful, glowing plants

Spider Caves

Full of Silk and Web, as well as Spiders

Horrifying Caves

Nothing spawns, but it looks very spooky

Molten Caves

Filled with Blackstone and Magma

Items

Kunai: throwing weapon

Two-handed swords: much stronger than regular swords

Silk balls: create webs on hit

Golden minecart: 10 times faster than a regular one, but sometimes derails

Copper Equipment

New armor and weapons

Titanium Equipment

Stronger than Diamond, but Iron damage and speed

Sulfur Ore

Used for crafting Gunpowder

Buried Church

Home for the Weeping Angels: immortal mobs similar to Creepers

Crystal Tower

Starts from the lower world and rises to Y=40

Dangerous Mine

Many reinforced Skeletons and loot