The main rivers forming the Kosi system are-
the Sun Kosi River, the Indravati River, the Bhote Kosi,
the Dudh Kosi, the Arun River, Barun River, and Tamur River.
The park has a total area of roughly 2799.08 sq km, Indravati attained the class of a National Park in 1981
and a Tiger Reserve in 1983 under the famous Project Tiger of India to become one of the most famous tiger reserves in India.