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, Saturn's satellite Enceladus, or on Titan, which has its surface covered with methane lakes. Despite the abundance of aquatic worlds, many of them are inaccessible as they orbit stars as far away as the planets that orbit stars.