- Not to be confused with placement layers.
Depth can be determined via a Depth Meter or any of its derivative accessories:
- On the Desktop version, Console version, and Mobile version, depth is measured in feet, with one tile equaling two feet.
- On the Old-gen console version, depth is measured in meters, with two tiles equaling one meter.
- On the version, depth cannot be measured, as informational tools are not available.
The Depth Meter numbers feet or meters above Level Surface, then feet or meters below Level Surface. Each reading includes a layer name: Space, Surface, Level Surface, Underground, Caverns, and Underworld. The range of numbers depends on platform, map size, and the randomized world generation of each world.
Space is the topmost layer. It is its own biome and does not contain other biomes. It generally contains no natural structures, although Floating Islands and Living Trees may occasionally extend into it. The Sun, Moon, and stars are visible here against a backdrop that is always black, regardless of the time of day. Gravity is reduced in space, making characters jump higher and fall more slowly. Harpies spawn here, and in Hardmode, Wyverns and Arch Wyverns . In small worlds, space represents less than a fifth of the map above the Level Surface line, ranging up to about half for large worlds.
The surface includes the Forests, Deserts, Corruption, Crimson, Jungle, Snow, Hallow, and Ocean biomes. Meteorite biomes will usually be found here when they generate. The entrance to the Dungeon is also found here. This layer also usually contains the world's Floating Islands, although these are generally located some distance above the main land mass. A surface Glowing Mushroom biome can be seeded here by players, but will never occur naturally.
Only in the surface layer will regular, Corruption/Crimson and Hallow grass naturally grow and spread (although grass can be planted with seeds or the Staff of Regrowth in other layers, it will not spread). Trees and Corruption/Crimson thorny bushes will only grow in the surface layer. Terrain blocks cover a large amount of the lower surface layer, with Dirt Wall behind them.
Areas below the actual terrain surface (areas the player must dig in order to access) are still considered "surface" if they are above the Depth Meter's "Level Surface" (0 feet). The lowest point of the actual surface will typically be 50 feet above this point.
The Surface and Space layers together represent about a quarter of the total world height. The height of the Surface layer varies far less with world size than does the height of the map itself, being less than half again as big in large worlds than in small ones.
The underground layer contains the same biomes as the surface layer. This layer begins at 0 feet, and extends downward for about 10% of the map height. It has a unique backdrop that depicts dirt with stones set in it.
The cavern layer contains the Ice biome, Underground Glowing Mushroom biome, and Underground Jungle biomes, which are each located beneath their surface versions. It additionally contains generic cavern features that fill the area between those distinct biomes (see cavern for details on generic cavern features). In Hardmode, the additional Underground Corruption or Underground Crimson, and Underground Hallow, will form. A large section of the Dungeon also extends through this layer.
The cavern layer may be subdivided into the upper and lower cavern layers. The main differences are that the Ice biome ends at the bottom of the upper cavern layer, and lava pools are common in the lower cavern layer but not generally found in the upper cavern layer except in a few situations such as adjacent to Underground Desert.
This is the largest layer and includes over half the map height, between the Underground and Underworld layers. This layer's backdrop is the same as that of the underground, except the dirt is of a darker hue, resembling stone.
This layer consists of the bottom 300-odd feet of the map, below the Caverns layer. Its backdrop is open space with magma pools and pillars. The Underworld is its own biome and does not contain other biomes within it. Lava is abundant here. Any water that flows into this layer disappears ("evaporates") quickly.
The World Banner depicts world layers.