Minecraft wiki entry for Superflat, associated text: The volume of an entire default superflat world, not including villages, bonus chests, or air, is 14.4 million km3, and the world is composed of 1.44×1016 blocks.
Because cloud height isn't affected by the world generation, clouds appear underground in the Tunneler's Dream preset.
If the player selects the desert preset, and remove all layers but sand, it is possible to create a massive, endless wave of falling sand. All one has to do to accomplish this computer-breaking feat is dig straight down to the bottom of the world. The sand then begins to fall from the initial digging coordinates.
Superflat was first conceived at the first MineCon and was intended for creative builds.[6]