Caverealms

This mod, borrowing from the concepts of skylands, creates huge underground caverns that extend for hundreds of blocks. Within these caverns lie stalagmites of glowing crystals, small glowing gems littering the floor, and variable terrain. Stalagmites and stalactites also spawn, and the texture as well as the structure of the crystal stalagmites has been improved. Not to mention plentiful lava and even water springs. Caves spawn between y = -700 and -33,000, and can be quite extensive.

Tthe caves have four biomes: moss, fungi, algae, and glaciated. The moss biome has blue crystal stalagmites and small glowing crystals on the ground, and moss covers the ground. The fungi biome has green crystal stalagmites highlighting the lichen-covered landscape, and luminescent purple mushrooms as well as green mycena mushrooms dot the ground, while giant mushrooms loom about. The algae biome is the least developed right now, but it features yellow-green algae covering the ground, and, on a slightly rare chance, glowing mese crystal stalagmites and stalactites. The glaciated biome has ground covered with two layers of ice, and has thin ice around the edges. Stalagmites and stalactites can be made of this ice as well, and the stalactites can be lethal as well: every time you dig a node of ice from them, there's a chance that the whole stalactite will come crashing down, greatly hurting or killing anyone standing beneath. (Note that there is an option in the config.lua file to turn this off.) Additionally, all biomes have glow worms hanging from the ceiling. There is also something special: the Dungeon Masters' Lair. Between y=-4000 and -5000 lies this treacherous place where nothing is hospitable. But exploring it is worth it, for the Fortresses found down there have chests full of somewhat valuable items within.