Nasa' s Cassini spacecraft has found evidence that points to the existence of an underground ocean of water and ammonia on this moon of Saturn. Which is the moon in question?

NASA's Cassini spacecraft discovered compelling evidence of an underground ocean of water and ammonia on Titan, Saturn's largest moon. The findings, announced in 2008, were based on Titan's rotation characteristics and the presence of ammonia, which acts as antifreeze allowing liquid water to exist beneath the icy surface. Io is a moon of Jupiter, Charon is Pluto's moon, and Titania is a moon of Uranus - none of which were discovered by Cassini to have this specific ocean composition.