Cave

A cave (also known as a cavern) is a common terrain feature that generates in the Overworld and the Nether. Caves are usually found underground. They are open spaces of various sizes and shapes that often intersect with each other or with different generated structures, creating vast cave systems. They feature an abundance of ores, as well as hostile mobs that spawn in the darkness.

Caves are a part of Minecraft's terrain consisting of randomly generated cavities of air, water or lava, creating a hollow area and exposing other blocks generated with the terrain (such as stones and ores).

Caves generate at any altitude up to Y-level 256, and may span from the surface all the way to Y-level -59. Because of low light levels, hostile mobs and certain animals like bats and glow squids (only in water) often spawn in caves.