M ars has some of the most intersting topographical features in the solar system. The canyon of Valles Marineris, is the largest and deepest known in the solar system. It extends for more than 4,000 km (2,500 miles) and has 5 to 10 km (3 to 6 miles) of elevation between its lowlands and the top of its plateaus. Two extremely large circular basins are located in the southern highlands, which are known as Hellas and Argyre. Hellas is 1,500 km (900 miles) across and 7 km (4.3 miles) deep, while Agryre is 800 km (500 miles) across and 2 km (1.2 miles) deep. Interestingly enough water was found at the Martian poles in the form of ice caps ice caps.