The western part of the leading hemisphere of Tethys is dominated by a large impact crater called Odysseus, whose 450 km diameter is nearly 2/5 of that of Tethys itself. The crater is now quite flat – more precisely, its floor conforms to Tethys's spherical shape. This is most likely due to the viscous relaxation of the Tethyan icy crust over geologic time. Nevertheless, the rim crest of Odysseus is elevated by approximately 5 km above the mean satellite radius. The central complex of Odysseus features a central pit 2–4 km deep surrounded by massifs elevated by 6–9 km above the crater floor, which itself is about 3 km below the average radius.