Sinharaja is mostly a rain forest. It is surrounded by misty mountains of Deniyaya from the South Kalawana from the East, Kukule Ganga from the North and Pelawatta from West. Most of the thick jungle is so richly grown that in many areas of the jungle the sunlight doesn’t reach the ground. Some of the tallest and biggest trees are found in the middle of the forest.

A large variety of valuable timber is found in the sanctuary area. A wide variety of Orchids, Butterflies etc. are seen but the wild animals are rare except a few Leopards, Sambhur and Wild Cats. Here and there are some gushing waterfalls colonies of wide variety of ants, reptiles and very especially large and long varieties leeches who are always hunting for blood. Sinharaja was declared a World Heritage by the UNESCO in 1988.