Here’s the countdown…
Volcano on Mars
A sheet like covering of lava.
The seven possible cave entrances on the flanks of Arsia Mons are collectively called the Seven Sister. Martian apes might have lived there :D! They’re 100 to 252 m wide and approximatly 73 to 96 m deep.
Borealis Basin or North Polar Basin covers 40% of the Martian surface and is low, flat and relatively crater free. Viking 1 landed near it.
Well, they’re mostly like Earth’s.
4000 km long, 200 km wide and 7 km deep, Valles Marineris is larger than any canyon on Earth, infact, its the largest canyon in the solar system! Its 6 times deeper than Grand Canyon and it would cover United States if placed on Earth!
Approximatly 3 times taller than Mount Everest and being the tallest mountain in the solar system, Olympus Mons wins the first position! It stretches 27 km (17mi).