Overhead view of the central region of the giant Valles Marineris canyon system on Mars, computer-processed from Viking spacecraft imagery and topographic maps of the planet. l. Valles Marineris is a system of canyons that runs along the Martian surface east of the Tharsis region. At more than 2,500 miles long, 120 miles wide and up to 23,000 feet deep, the Valles Marineris rift system is one of the larger canyons of the Solar System. Valles Marineris is located along the equator of Mars, on the east side of the Tharsis Bulge, and stretches for nearly a quarter of the planet's circumference.