| Asopus Vallis | |
| Coordinates: | -4.4°N -149.7°W |
| Naming: | a classical name for the modern Hagios River, Greece |
Asopus Vallis is a valley in the Memnonia quadrangle on Mars, located at 4.4° south latitude and 149.7° west longitude. It is 33 km long and was named after a classical name for the modern Boeotian Asopus river in Greece.[1]