The Koshi Tappu Wildlife Reserve is a protected area in the Terai of eastern Nepal covering 175 km2 (68 sq mi) of wetlands in the Sunsari, Saptari and Udayapur Districts. In altitude it ranges from 75 to 81 metres (246 to 266 ft) and consists of extensive mudflats, reed beds, and freshwater marshes in the floodplain of the Sapta Kosi River. It was established in 1976 and designated as a Ramsar site in December 1987.
It can be accessed from the Mahendra Highway. A study of the reserve was conducted between 1997 to 1998 by the Central Department of Zoology, Tribhuvan University in Kathmandu.
The study found serious conflicts between the reserve wildlife and the local people living adjacent to the reserve. The people suffered crop depredations and animal harassment while the reserve managers had the problems of poaching, cattle grazing, and other illegal activities in the reserve. The study has several recommendations, one of which is the promotion of tourism to the area with the reserve using local tourist guides trained by wildlife experts.