Great Kei River, river, Eastern Cape province, South Africa. Formed southeast of Komani (formerly Queenstown) by the junction of the White Kei (Wit Kei) and the Black Kei (Swart Kei) rivers, it flows approximately 140 miles (225 km) southeast to the Indian Ocean. Its longest tributary is the Tsomo (north). The river and its headwaters follow winding courses.