Olympus Mons is the highest mountain in the solar system. Its peak is 25 km (15 miles) above its base – nearly three times the height of Mt. Everest. Olympus Mons is desginated a shield volcano because of its shape. Despite its great height, it has a very gentle slope. Olympus Mons is over twenty times wider than it is high.

It is the same kind of volcano as the active volcanoes currently ‘creating’ the Hawaiian Islands. The line around Olympus Mons is a ‘basal cliff’ which is as high as 6 km (3.72 miles) in some places.