This ocean may be twice the volume of Earth's oceans combined, and could contain more than twice as much water as all of Earth's oceans.
A moon of Saturn, Enceladus has an active plume of water vapor and ice particles emanating from its south pole, indicating the presence of a subsurface ocean.
Another moon of Saturn, Titan has seas and lakes of liquid methane and ethane on its surface, making it the only other known world besides Earth to have stable bodies of liquid on its surface.
The largest moon of Neptune, Triton has a subsurface ocean that is believed to be in contact with a layer of warm rock, potentially providing a source of energy for life.
The largest moon of Jupiter, Ganymede is also believed to have a subsurface ocean, as well as a thin atmosphere and a magnetic field.
Another moon of Jupiter, Callisto has a heavily cratered surface and is believed to have a subsurface ocean that may be in contact with a layer of rock, potentially creating an environment suitable for life.
A moon of Saturn, Dione is believed to have a subsurface ocean and may have a layer of liquid water between its icy shell and rocky core.
Although not technically an ocean world, this large mare (or plain) on the Moon is named after the "Ocean of Storms" and is believed to have been formed by ancient volcanic activity.