There are 4 ocean planets and 11 ocean moons in our solar system. All ocean worlds have subsurface saltwater oceans except for Io, which as a subsurface magma ocean. Earth of course has surface oceans.

Ocean world facts

A number of ocean worlds past the snow line (between Mars and Jupiter) are "active" where their subsurface ocean punches through the crust and forms active cryovolcanoes or cryogeysers. Note that Ganymede and Europa have oceans that exceed the volume of Earth's ocean. That's a lot of water.

Name Class Ocean Volume* Active
Callisto moon 4
Ceres dwarf planet cryovolcanoes
Dione moon 10
Earth planet 3
Enceladus moon cryogeysers
Eris dwarf planet 7
Europa moon 2 cryovolcanoes
Ganymede moon 1
Mimas moon
Oberon moon 9
Pluto dwarf planet 6 cryovolcanoes
Titan moon cryovolcanoes
Titania moon 8
Triton moon 5 cryogeysers
Io** moon volcanoes

* Volume = 1 is the the largest ocean(s)
** Io has a subsurface magma ocean

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