The Great Kei River is a river in the Eastern Cape province of South Africa. It is formed by the confluence of the Black Kei River and White Kei River, northeast of Cathcart. It flows for 320 km (199 mi) and ends in the Great Kei Estuary at the Indian Ocean with the small town Kei Mouth on the west bank. Historically the Great Kei River formed the southwestern border of the Transkei region as was formerly known as the Nciba River.
The Great Kei River is a meandering river course and is formed by the convergence of the Black Kei River and the White Kei River in Enoch Mgijima Local Municipality, north-east of Cathcart and southeast of Queenstown. The Great Kei river flows from the junction of the Black and White Kei rivers for approximately 225 kilometers (140 miles) southeastwards along winding courses to the Indian Ocean. It terminates at the Great Kei estuary by Kei Mouth, a coastal resort town. Its longest tributary is the Tsomo in the north. The name has it origins as far back as 1752 and is based on a Khoisan word for the river meaning ‘sand’.
The Great Kei previously formed the southwestern border of the Transkei region which can be accessed via the ‘Pont’, one of only two car-transporting river ferries in South Africa. The pont is currently operational and motorists are frequently ferried from the southwestern bank to the northeastern bank into the Wild Coast.
The estuaries from the Great Kei river to southern Mozambique are classified as subtropical. These systems are characterized by warm waters of more than 16 degrees Celsius. The climate is warm and humid almost year-round as a result. Minimum winter temperatures range from 12- 14 degrees Celsius and the area receives rainfall throughout the year.
The inland sections of the Great Kei River flow through Albany thickets and Forest biomes, terminating in Indian coastal thicket at its mouth. The Kei river mouth hosts the southernmost naturally occurring mangrove forests in Southern Africa. Swamp forests occur north of the Mngazana estuary, and salt marshes are found south of the Great Kei estuary. The Great Kei river mouth is popular with anglers due its variety of estuarine fish species. However, some species such as the South African Cob and White steenbras are critically endangered. Many coastal bird species are found in the area such as the near-threatened African oystercatcher, sandpipers, and kingfishers.