The Orange River, Delineating the Border between South Africa and Namibia
The Orange River, the dark line through the center, is the longest river in South Africa, with a total length of 2200 km (1367 mi).
It rises in the Drakensberg mountains in Lesotho (where it is known as the Senqu River), and flows westwards through South Africa to the Atlantic Ocean.
The river forms part of the international borders between South Africa (below) and Namibia (above) and between South Africa and Lesotho (not visible here), as well as several provincial borders within South Africa.
Although the river does not pass through any major cities, it plays an important role in the South African economy by providing water for irrigation, as well as hydroelectric power.