The spectacular avifaunal diversity present in the Jim Corbett National Park owes its survival to the two rivers that flow through the park - the Ramganga (West) and River Kosi. The Ramganga along with its tribuataries, Palain, Mandal and Sonanadi serve as the key hydrological resource for the park.

This river which is a tributary of the mighty Ganges, originates in the Doodhatoli ranges of the Himalayas and flows out south-west to pass through the Corbett. The river is much popular amongst anglers for the 'Mighty Mahseer' - the fighting fish. The endangered fish eating ghariyal can also be seen in the Corbett stretch of the river. Kosi flows in close proximity to the park and not properly through it, yet it provides for the birds and animals in the park a cruical source of water, especially so during the dry season.

However, due to its presence at the tourist hub Dhikuli where most of the tourist hotels and resorts are located, the River Kosi has a more immediate connect with the travellers to the region.

For angling and fishing enthusiasts, the best time to visit the Jim Corbett National Park is from early October to mid December and then again from mid of February for the next four months.

The Tarangi Resort in Corbett is located on the banks of the River Kosi.