Mars giant underground mass has been uncovered beneath Tharsis Montes, spanning 1,750 kilometers at 1,100 kilometers deep—disrupting planetary science with its scale and location near Olympus Mons. Researchers call its presence a seismic surprise.

Experts now suspect the Red Planet’s interior may hold more active secrets, with new data suggesting Mars volcanoes could still erupt. The discovery challenges basic geology, hinting at future Mars missions dodging subterranean giants on the hunt for water.