The rugged Teesta River, the main river of Sikkim, Darjeeling, and Kalimpong Hill Region, with a series of rapids with varying intensity, has been rated at Grade 4. The turbulent Rangit, a tributary of the Teesta, with its multi-dimensional rapids, it offers a challenge to more experienced rafters. In Teesta rafting is confined to the winter months, between October and April. Spring or early summer is ideal for river rafting. Paddle rafting and oar rafting can be done in the Teesta River.