Where is the largest valley in the solar system?
September 18, 2020 | Education
| The largest valley currently known is the Mariner Valley on Mars. It is a huge canyon over 4000 km long, 120 km wide and 5-6 km deep.

The largest valley currently known is the Mariner Valley on Mars. It is a huge canyon over 4000 km long, 120 km wide and 5-6 km deep.