Rathong River originates as a small stream from the Doodh Pokhri (Milk Lake). The river then steeps downwards in the southern direction towards Yuksom
The road from Legship follows the river for about 48 km via Tashiding. The trek route to Yuksom is by the sides of the Rathong. Rangit Water World, a water theme park, operates at the convergence of Rangit and Rathong River.