Aquatic creates encompass life that is primarily adapted to life underwater, commonly in the great sea. They usually need water to breathe. Related but distinct is Amphibious life, which can breathe both under and over-water.
There is an unknown depth and variety of aquatic creatures, as the depths of the sea remain a difficult to penetrate and survive frontier of exploration.
The deep seas are thought to be a Plane in itself, and likely home to the Ocean King if he exists. The lowest plane in the Great Flow, Abbadon, is compared to the deep ocean floor.