The Koyna River is a tributary of the Krishna River which originates in Mahableshwar, Satara district,western Maharashtra, India. It rises near Mahableshwar, a famous hill station in the Western Ghats. Unlike most of the other rivers in Maharashtra which flow East-West direction, the Koyna river flows in North-South direction. The Koyna River is famous for the Koyna Dam and the Koyna Hydroelectric Project. Today the Koyna Hydroelectric Project is the largest completed hydroelectric project in India.