An artist's conception of what the surface of an ocean planet.
Ocean planets are a type of planet whose surface is covered
completely by water. The oceans would be hundreds of kilometers
deep and at the bottom, water would become ice because of
extreme pressure caused by the ocean water on top.  An artist's
conception of an ocean planet. GJ 1214b is a recently discovered
ocean planet that is ~42 Light-years away from Earth.  - ↑ Ocean
Planets on the Brink of Detection - ↑ Link