forest reserve is situated in northeast of Galle along the main road to Udugama township. This isolated patch of low country rain forest is only about 37 acres in extent. Nevertheless, it has all the features of a typical rainforest. The vegetation is that of wet evergreen type with tall trees struggling upwards to reach the sunlight with small canopies touching each other preventing the penetration of sunlight to the bed of the forest. The tree bases are buttress in nature, a well represented under storey of plant comprising of the dominate tree species is present and hence it is considered a climax community, a healthy sign for the continuity of the forest. The vegetation is dominated with Dipterocarpus Species and Tree Ferns, where Orchids and Moss grow on their tall tree trunks.
There are about 170 tree species identified in the area of which about 100 species are endemic to the country. About 80 common tree species have been identified and numbered with their botanic names. In Kottawa Arboretum can be able to observe about 70 species of birds, including 12 endemics, such as Yellow-fronted Barbet, Brown-capped Babbler, Spot-winged Thrush, Sri Lankan Spurfowl and Grey Hornbill. It is also a good place to see some beautiful Sri Lankan butterflies (Birdwing, Tree Nymph, Clipper, Blue Oakleaf and more).
The Purple-faced Leaf Monkey, Toque Monkey and Giant Squirrel dominate the canopy area of the forest. Among the reptiles, some beautiful Sri Lankan non-venomous snakes and some endemic agamid lizards could be found in the area. The unpolluted streams that traverse through the forest area harbours a variety of fresh water fishes of which most of them are endemic to the country.