Kanneliya Rain Forest was designated as a biosphere reserve in 2004 by UNESCO. The forest has the richest flora in South Asia. It is situated 35 km northwest of city of Galle district approximately 170 km from Colombo. This rain forest serves as the catchment area for two important rivers in Southern Sri Lanka, the Gin and Nilwala Rivers. This biosphere reserve harbours many plants and animal species native to Sri Lanka.
17 percent of lowland endemic floral species are confined to this rain forest area. Numerous medicinal plants such as Coscinium fenestratum, Salacia reticulata, and Salacia reticulata and some of the rarest plants such as Lycopodium squarrosum and Lycopodium phlegmaria are found in this area.
Out of 26 endemic birds of Sri Lanka, 20 of them can be seen in the forest reserve.