The Cavern layer is the largest layer. Its backdrop is the same as that of the Underground, except the dirt is of a darker hue, resembling stone. It contains the Ice biome, Underground Jungle, and Underground Desert biomes, which are each located beneath their surface versions, as well as Underground Glowing Mushroom biomes.

The change of background that marks the beginning of the Cavern layer. The Cavern layer is the largest layer of the world, beginning just below the Underground and extending down until the Underworld layer. Darker stone background tiles characterize it. Stone is the predominant block in this layer (as opposed to Dirt in the Underground).