662-mile-wide Tethys, as seen by Cassini on March 3, 2010. Part of the 1200-mile-long Ithaca Chasma can be seen on its western edge, running north to south. With a density .97 times that of liquid water, Tethys is almost completely made of ice.
Image has been adjusted to bring out surface details.
Image: NASA/JPL/Space Science Institute