Okavango, river in southern Africa, flowing in Angola, Namibia, and Botswana. The Okavango rises in the Bié Plateau of Angola, where it is known as the Cubango. It flows south, then southeast to the Angola-Namibia border. As it continues east along this border for about 400 km (about 250 mi), the Okavango is joined by the Cuito, its only major tributary. The river then turns south to cross the Caprivi Strip (a narrow eastern extension of Namibia) and enter Botswana. Its southeasterly course into the Okavango Delta (also called the Okavango Swamp) is controlled by two faults, or fractures in the earth's crust, that run parallel to the river. In the delta, the Okavango's waters spread out through a complex web of vegetation-choked channels and into shallow basins. Virtually all of the river's water evaporates in the delta; about 3 percent flows out via the Boteti River and two other, usually dry, outlet channels. This outflow flushes salts from the delta, thus preserving its freshwater ecosystem. The river is 1,800 km (1,120 mi) long, and drains an area of about 785,000 sq km (about 303,000 sq mi). The Okavango takes its name from the Okavango people of northern Namibia.

Scientists believe the Okavango was once a much larger river that flowed southeast into the Limpopo River and then into the Indian Ocean. After regional earth movements severed the connection to the Limpopo, the Okavango's waters collected to form Makgadikgadi Pan. Further earth movements and a long-term decline in rainfall reduced the river's flow, causing Makgadikgadi Pan to dry up and creating the present delta.

The Okavango passes from dense woodland savanna near its source through increasingly arid savanna as it enters northern Botswana. The delta area has distinctive vegetation, with dense beds of papyrus and other aquatic plants in the water, as well as woodland on the dry areas, or islands. Species of fish found in the Okavango include barbel, bream, bulldog fish, sharp-toothed catfish, and tiger fish. The volume of the river fluctuates greatly between the dry season and the rainy season. The rainy season varies in length throughout the Okavango Basin, lasting significantly longer at the source of the river than in the delta. The floodwaters that move slowly downstream during the rainy season reach the delta in March. Migration and reproduction of wildlife revolve around the timing of these floods.

The Okavango Basin contains few people. The river's resources are largely unused, except for subsistence fishing, herding, and farming by groups such as the Batawana and the Bayei in the Okavango Delta and the Okavango in Namibia. In Botswana, there are increasing pressures to divert water from the delta for livestock rearing, irrigation, and diamond mining (where large quantities of water are needed to wash the crushed ore, so that the diamonds become separated from the rest of the material). Growing numbers of tourists, however, are visiting the delta to see the region and its wildlife.