Nepal's first and most famous national park is situated in the Chitwan Doon or the lowlands of the inner Tarai. Covering an area of 932 sq. km. The park includes hilly areas of the siwalik range covered by deciduous sal forest. A fifth of the park is made up of the floodplains of the Narayani, Rapti and the Rue rivers and is covered by dense tall elephant grass interspersed reverine forests of silk Colton (kapok), acacia and sisam trees. Besides rhino and tiger, Chitwan also supports a great variety of flora and fauna.

There are four species of deer, including the spotted chital, leopard, sloth bear, wild boar, rhesus monkey, gray langur monkey, wild dog, small wild cats, the white stockinet gaur (the world's largest wild cattle) and many other smaller animals.

The swampy areas and numerous ox-bow lakes of Chitwan provide a home for marsh crocodiles. In a stretch of the Narayani River is found one of the few remaining of populations of the rare and endangered fish-only eating Gharial or Genetic crocodile. Here also is found one of the world's four species of fresh water dolphins. For the ornithologist and the amateur bird watcher the park offers excellent possibilities with more than 450 species. Some of the resident specialties are peacocks. Several species of woodpeckers, hornbills, Bengal florican, and red headed trogons. Winter birds such as waterfowl, Brahmiuny duck, pintails and bar headed geese, amongst many other cold weather visitors are drawn by the sanctuary of the parks is with alive nesting migrants such as the fabulous paradise flycatcher, the Indian Pitta and parakeets.