Tirawa Basin on Reha, from Voyager 1 (Natural Colors; credits: Ted Stryk)

As Voyager 1 receded from its close flyby of Rhea, it snapped this view of Rhea's Tirawa Basin, a large impact structure seen on the Terminator in this crescent view.
It is on of the worst-imaged parts of this world, and this Voyager view is still the best. Rhea is a moon that shows some similar features to more active Dione and Tethys, but seems to have been inactive for longer, as evidenced by the fact that all of its surface is extremely worn from impacts and the evidences of internal activity are much more subtle.