The river basin measures 10,622 km2 (4,101 sq mi) in size, with the drainage divided by the Gbengbe and Kabala hills and the Sula Mountains.

[2][3] The Rokel rises in the 900 metres (3,000 ft) high interior plateau of the Loma Mountains, in the Guinea Highlands of north central Sierra Leone, flows southwest about[vague] 240 miles (390 km) through hill ranges and, together with a smaller, parallel stream called Port Loko Creek, feeds into the Rokel estuary before entering the Atlantic Ocean.

[4] The river basin measures 10,622 square kilometres (4,101 sq mi) in size, with the drainage divided by the Gbengbe and Kabala hills and the Sula Mountains.

[7] Mangrove species recorded are Rhizophora, Avicennia, Laguncularia, and Conocarpus, which cover an area of 34.23 hectares (84.6 acres).

[9] John MacCormac, an Irish businessman, settled on Timbo Island in 1816 and started exporting African Oak from the Rokel River.

Iron ore and alluvial gold mining began in the late 1920s and early 1930s, while the Bumbuna Falls hydroelectric project is underway.

[11] The estuary, which extends over an area of 2,950 square kilometres (1,140 sq mi), was listed as Ramsar site of wetland importance in 1999.

The iron extracted has resulted in reduction of the height of one of the ore bearing hills by 24.4 metres (80 ft).

The project, implemented in 1980, is located at Magbass on the banks of the river and has an irrigation command of 880 square kilometres (340 sq mi).