A river, about 2,092 km (1,300 mi) long, of Lesotho, South Africa, and Namibia flowing southwest, northwest, and west to the Atlantic Ocean. It is used extensively for irrigation. River, southern Africa. It rises in the Lesotho Highlands as the Sinqu River and flows west as the Orange across South Africa. It passes the southern edge of the Kalahari Desert and winds through the Namib Desert before draining into the Atlantic Ocean in South Africa. It forms the border between South Africa and Namibia. It is about 1,300 mi (2,100 km) long. There are some irrigated sections along the river and many dams but no large towns