Enceladus, one of Saturn's moons of only about 314 miles in diameter hides in its entrails an ocean of liquid water that is rich in organic molecules, making it one of the places where it is most likely to find some form of extraterrestrial life.
Europa is a strange shaped moon of Jupiter with a large number of intersecting lines. Models from the interior of Europe show that under a thin crust of 5 km (3 miles) of water ice, Europa can have oceans with 50 km (30 miles) of depth or more. The visible marks of Europa could be the result of a global expansion where the crust could have been fractured, filled with water and frozen.