Nicknamed the Death Star due to its resemblance to the Star Wars super weapon.
(http://upload.wikimedia.org/wikipedia/commons/thumb/b/bc/Mimas_Cassini.jpg/250px-Mimas_Cassini.jpg)
Astronomers at Cornell University, think this Moon may have an ocean beneath its frozen surface further increasing the number of potential sites for water based life in the Solar System.
QuoteMimas is a moon of Saturn which was discovered in 1789 by William Herschel. It is named after Mimas, a son of Gaia in Greek mythology, and is also designated Saturn I.
With a diameter of 396 kilometres (246 mi) it is the twenty-first-largest moon in the Solar System and is the smallest astronomical body that is known to be rounded in shape because of self-gravitation.
http://en.wikipedia.org/wiki/Mimas_%28moon%29
Here is the abstract from the paper with my emphasis.
QuoteLike our Moon, the majority of the solar system's satellites are locked in a 1:1 spin-orbit resonance; on average, these satellites show the same face toward the planet at a constant rotation rate equal to the satellite's orbital rate. In addition to the uniform rotational motion, physical librations (oscillations about an equilibrium) also occur. The librations may contain signatures of the satellite's internal properties. Using stereophotogrammetry on Cassini Image Science Subsystem (ISS) images, we measured longitudinal physical forced librations of Saturn's moon Mimas. Our measurements confirm all the libration amplitudes calculated from the orbital dynamics, with one exception. This amplitude depends mainly on Mimas' internal structure and has an observed value of twice the predicted one, assuming hydrostatic equilibrium. After considering various possible interior models of Mimas, we argue that the satellite has either a large nonhydrostatic interior, or a hydrostatic one with an internal ocean beneath a thick icy shell.
SOURCE: http://www.sciencemag.org/content/346/6207/322
Other potential sites include beneath the surface of Mars (where liquid water could well exist) and Europa which is thought to have a water ocean beneath a frozen crust.
(http://upload.wikimedia.org/wikipedia/commons/thumb/5/54/Europa-moon.jpg/600px-Europa-moon.jpg)