The South Alligator River is also about 160 km long. It rises north of Mount Stow, on the Arnhem Land Plateau. It flows northwesterly in a valley containing a number of disused uranium mines developed between 1955 and 1965. It also flows out into the Van Diemen Gulf of the Timor Sea. The catchment area occupies an area of 11,917 km2 and has the East Alligator River catchment to the east, the Wildman and Mary River catchments to the west, and the Daly River catchment to the south.
