Minecraft wiki entry for Things_not_to_do, associated text: When doing a survival world, the player should avoid creating a superflat world with water as the only block preset. This setting does not generate land. The player swims and eventually drowns, or runs out of food and starves to death. A superflat world with just water can be boring. The player can use this preset for making a Creative Mode world, to enjoy painful experiences such as Dark Souls, or to have set certain structures to spawn within the world.