Several bodies in our solar system are believed to harbor subsurface oceans. Europa, a moon of Jupiter, likely contains a global ocean beneath its icy crust, with an estimated volume twice that of Earth's oceans. Enceladus, a moon of Saturn, ejects plumes of water vapor and ice particles from its south pole, strongly suggesting a subsurface ocean with hydrothermal activity. Titan, Saturn's largest moon, has surface lakes of liquid methane and ethane, and likely a subsurface water ocean. These extraterrestrial oceans are prime targets in the search for life beyond Earth.