The great majority of the land, particularly in the hills, remains unvisited and therefore undisturbed. This is ideal for wildlife, and also preserves an element of mystery for humans; because large areas are still unexplored, our knowledge of what birds and animals the park contains is by no means finalized, and there is always the possibility of making new discoveries. 

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). It was established in 1976 and designated as a Ramsar site in December 1987. Koshi Tappu is a rectangular shaped reserve, approx. of 10 km width and 10 km length stretching northward from the Nepal-India border along the Sapta Koshi River. The vegetation is mainly tall grassland(khar-pater) and offers important habitat for a variety of wildlife. Most of the habitat found here are the protection of Wild buffalo along others animals like hog deer, wild boar, spotted deer, gharial, gaur, pangolin, gangetic dolphin, monitor lizard and python, chital, hog deer, barking deer, sloth bear, langur, rhesus monkey, etc.  

The reserve also permits to have a fishing. A total of 290 different species of birds have been recorded in the reserve. The Koshi Barrage is extremely important as a resting place for migratory birds and many species recorded there are not seen elsewhere in Nepal. Koshi Tappu Wildlife Reserve is one of the finest birding sites in Asia. The endangered Gharial crocodile and Gangetic dolphin have been well preserved in the Koshi river. One can observe the migratory and resident birds on the main river channel. Mountain ranges including Makalu (8475 m) the world's fifth highest mountain, can be seen.

Reference: https://www.fittnepal.com/blog/short-introduction-on-koshi-tappu-wildlife-reserve

Picture Reference: From facebook profile of Ritika Prasai sister (https://www.facebook.com/ritika.prasai)