chief river system of Ghana, formed from the confluence of the Black Volta (Black Volta River) and White Volta (White Volta River) (qq.v.) headstreams. The Volta flows generally southward through Ghana, discharging into the Gulf of Guinea. Its major tributaries are the Afram and the Oti (Pandjari). The river system has a length of 1,000 miles (1,600 km), a drainage basin of 153,800 square miles (398,000 square km), and an average annual discharge of 42,700 cubic feet (1,210 cubic metres) per second.

Both of the river's two main upper branches, the Black (Black Volta River) and White Voltas (White Volta River), rise in the open plateaus of Burkina Faso (formerly Upper Volta) and unite in north-central Ghana some 300 miles (480 km) north of the sea. (These two branches are respectively called the Mouhoun and the Nakambe rivers in Burkina Faso.) The Volta's lower course was well-known to Europeans since the time of the 15th-century explorations of the Portuguese, who gave it its name, meaning “turn,” because of its twisting course.

The northern four-fifths of the Volta River's valley is now covered by Lake Volta (Volta, Lake), which is one of the world's largest artificial lakes. Lake Volta was formed after the Akosombo Dam (q.v.) was completed in 1965; the dam was built at the gorge where the Volta River cut through the Akwapim-Togo Ranges on its way to the sea. Below the damsite, the Volta River turns sharply eastward across the Accra Plains before entering the Atlantic Ocean at Ada. See also Volta, Lake.