If Mars had a hall of fame, Earth would not make the cut. The solar system's tallest volcano, its longest canyon, and the deepest place you could stand and look up all belong to the red planet. Here are seven of them.
Olympus Mons: the volcano Everest can't match
Olympus Mons is the tallest volcano — and the tallest mountain of any kind — in the solar system. It rises about 22 kilometers above the Martian lowlands (NASA's laser altimeter measured 21.9 km): nearly two and a half Everests stacked end to end. Its base spans around 600 kilometers, roughly the area of Arizona, yet its slopes are so gentle a hiker might barely feel the grade. Lava flows on its flanks date to only a couple of million years ago, so geologists call the giant dormant rather than extinct.
The Tharsis Montes: three more giants in a line
Olympus Mons stands at the edge of Tharsis, a volcanic plateau that bulges roughly 10 kilometers above Mars's average surface. Along its crest sit three more shield volcanoes in a nearly straight row: Ascraeus Mons, Pavonis Mons, and Arsia Mons, north to south. Each is 350–400 kilometers across and rises roughly 17 kilometers above the surrounding plain (Ascraeus Mons tops 18 km), and Arsia Mons carries the largest volcanic crater on Mars, about 120 kilometers wide.
All four giants were found in 1971 by Mariner 9 — which arrived to find the entire planet hidden by a dust storm, then caught the volcano summits poking through as the first visible features. Mars could build such monsters because it never developed plate tectonics: on Earth, drifting crust keeps carrying volcanoes away from their magma supply, but on Mars the hotspot stays put and the same peak keeps growing for eons.
Valles Marineris: a canyon the Grand Canyon can't touch
Mariner 9's namesake canyon runs more than 4,000 kilometers along the equator east of Tharsis — roughly a fifth of the way around the planet. It stretches up to 200 kilometers wide and 7 kilometers deep: about ten times longer, twenty times wider, and five times deeper than the Grand Canyon (NASA's figures). It opened as the Tharsis bulge rose and the crust stretched, cracked, and dropped in a colossal rift.
Hellas Planitia: the deepest hole in the solar system
At the opposite end of the drama scale sits Hellas Planitia, a 2,300-kilometer impact basin — the largest well-preserved one on Mars — gouged out some 4 billion years ago by an asteroid. Its floor sits 7,152 meters below the Martian datum, the lowest point on the planet (ESA).
Gale Crater: the mountain Curiosity is still climbing
Curiosity landed in the 154-kilometer Gale Crater in August 2012 and has been climbing its 5.5-kilometer central peak — Aeolis Mons, better known as Mount Sharp — ever since. The peak is a layer cake of billions of years of sediment, and the rover has been reading it page by page, tracing Mars's long shift from wet to dry.
Jezero Crater: the delta that brought Perseverance
Jezero Crater, about 49 kilometers across, holds a preserved ancient river delta — one of the best places to hunt for signs of past life. That is why NASA sent Perseverance there in February 2021. The rover is now sealing rock samples in tubes on the surface, waiting for a future mission to bring them home.
The north polar cap: a climate archive in ice
Mars wears two polar caps that grow and shrink with the seasons. Beneath the seasonal carbon-dioxide frost lies the residual north cap — mostly water ice, stacked in fine layers. Each layer records how dust and ice accumulated during past swings of Mars's tilt, making the cap a climate archive stretching back millions of years. With no trees and no oceans, an ice cap is the next best diary.
The deeper tour
Two of these — Valles Marineris and Olympus Mons — already headline the Landmarks section on our homepage. Consider this post the extended visit. Mars did not just build the solar system's superlatives; it left them sitting out in the open, waiting for the day someone walks up to them in person.