Ithaca Chasma (Tethys)

An Ionian island, home of Odysseus.

Ithaca Chasma is up to 100 km wide, 3 to 5 km deep and 2,000 km long, running approximately three-quarters of the way around Tethys' circumference, making it one of the longer valleys in the Solar System. Ithaca Chasma may have originated when the water ocean inside Tethys froze. This would have caused the surface to crack in order to accommodate the resulting increase in volume. (wikipedia entry)

A chasma is a deep, elongated, steep-sided depression. On Tethys they are named after people and places from Homer's Odyssey.