The 440-mile Tana River is the longest river in Kenya, and gives its name to the Tana River District. The river rises in the Aberdare Mountains to the west of Nyeri. Initially it runs east before turning south round the massif of Mount Kenya. The river then turns into the Masinga Reservoir and the Kiambere Reservoir created by the Kindaruma dam. Below the dam the river turns north and flows the north-south boundary between the Meru and North Kitui and Bisanadi, Kora and Rabole National Reserves. In the reserves the river turns east, and then south east. It passes through the towns of Garissa, Hola and Garsen before entering the Indian Ocean at Ungwana Bay.