Kosi Tappu wildlife Reserve is very popular destination for wildlife activities. 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. It comprises extensive mudflats, reed beds, and freshwater marshes in the floodplain of the Sapta Kosi River, and ranges in altitude from 75 to 81 m (246 to 266 ft).
The Kosi Tappu Wildlife Reserve is home to 485 spices of Birds of which 12 species are globally threatened. The notable ones are water-cock, Indian night-jar, Dusky eagle owl, Black headed cuckoo, Common golden eye etc. The animals such as Elephant, Wild boar, Deer, Jackal and the Wild Water Buffalo (Arnas) are some of the animals of this reserve.Bird watching, Elephant ride, Jungle drive, Canoeing, Jungle walking, Village tour and Culture program are main popular activities in this reserve.