Wikipedia has some more information about this moon I've not previously heard of. The moon itself is composed largely of water ice and the liquid part is 15-20k

Wikipedia has some more information about this moon I've not previously heard of. The moon itself is composed largely of water ice and the liquid part is 15-20km under the surface. Mimas is responsible for the gap between Saturns widest rings and as you expect is splattered with craters, the largest of which is nearly 1/3 diameter of the whole moon. Looks like a disguised (or dilapidated!) Death Star.