Krubera Cave in the republic of Georgia is currently the deepest known cave, at 7,208 feet. But Dark Star, with so many areas still to survey, is a prime candidate to take over the title.

The beast was added with 1.20 The Wild update, and it only spawns in the Deep Dark biome if you make too much noise while walking, placing or breaking blocks, fighting, etc. Hence, this cave biome ...