This cavern opening is found on a lava plain in the volcanic Tharsis region of Mars. It’s so dark and deep that even the Mars Reconnaissance Orbiter’s sensitive cameras cannot peer into its depths. It’s probably a collapse pit formed when a lava tube or similar structure underneath the surface gave way. The entrance walls may actually be overhanging, concealing a space who knows how large, that hides who knows what.

Location: Mars

Released: 23.May.2007