Caldera and Elysium. Each province contains a series of giant shield volcanoes that are similar to what we see on Earth and likely are the result of mantle hot spots. The surfaces are dominated by lava flows, and all have one or more collapse calderas. Mars has the largest volcano in the Solar System, Olympus Mons, which is more than three times the height of Mount Everest, with a diameter of 520 km (323 miles). The summit of the mountain has six nested calderas. Because there is no plate tectonics on Venus, heat is mainly lost by conduction through the lithosphere.
Highest unclimbed mountain Highest unclimbed mountain An unclimbed mountain is a mountain peak that has yet to be climbed to the top. Determining which unclimbed peak is highest is often a matter of controversy. In some parts of the world, surveying and mapping are still unreliable, and there are no comprehensive records of the routes of explorers, mountaineers and local inhabitants. In some cases, even modern ascents by larger parties have been poorly documented and, with no universally recognized listing, the best that can be achieved in determining the world's highest unclimbed peaks is somewhat speculative. Most sources indicate that Gangkhar Puensum ()