Olympus Mons is a volcanic mountain on Mars. It’s 624 km in diameter (approximately the same size as the state of Arizona) and it’s height is about 22 km. It’s the highest volcano of the Solar System, and the second highest mountain. Its caldera is 80 km wide and has a depth of about 3 km.

To compare, the largest volcano on Earth is Mauna Loa. Mauna Loa is a shield volcano 10 km (6.3 mi) high and 120 km (75 mi) across. The volume of Olympus Mons is about 100 times larger than that of Mauna Loa. In fact, the entire chain of Hawaiian islands (from Kauai to Hawaii) would fit inside Olympus Mons!