Underground ocean found on Saturn's moon Mimas. Discovery on the satellite shows that these types of seas, where there could be life, are abundant in the Solar System.

In addition to Europa, there are at least seas inside Ganymede, Enceladus and Titan. It seems more difficult to reach the newly discovered Mimas Sea, hidden by a surface that seems inert by a gravity that could shake the satellite's core. But there are already crazy ideas that space agencies are listening to as possible long-term plans.