Superflat

Superflat is a World Type, first introduced to Minecraft in Snapshot 12w01a, replacing the normal varied terrain of The Overworld with a thin flat layer of dirt.

The terrain consists of one layer of Bedrock, two layers of Dirt, and one layer of Grass; the surface of the world is completely flat and at height y = 4. Since the height limit (128) is unchanged, there is then slightly less than twice as much vertical height available to build above-ground structures as compared to a normal world. Mobs spawn as normal, including slimes; however, there is no “void fog” as would ordinarily be caused by being close to the bottom.

The Nether and The End generate normally; they are not flat. In order to create a superflat world in SMP, the level-type flag in server.properties must be "FLAT", instead of "DEFAULT".

Bugs

 * If one breaks the Bedrock barrier, then one can see that the Void has the same color of the sky when the Player is above y=0, but looks normal (black) when the Player is below y=0.
 * There is no consistent spawn point unless you have slept in a bed; you may respawn far from your previous location without anything in sight. This may be due to the lack of ground at the usual height of about 64.