Sri lanka is one of the greatest wildlife watching countries in South Asia. Visitors are allowed in to these reserves where you can take safari trips with a trained guide provided by the reserves themselves. Here are some wildlife sanctuaries to take part,

Bundala National Park (between Hambantota and Kataragama)
Gal Oya National Park (north of Yala)
Horton Plains National Park (in the southwestern mountains)
Lahugala National Park (west of Pottuvil)
Uda Walawe National Park (near Hambantota)
Udawattakele Wildlife Sanctuary (northeast of Kandy)
Peak Wilderness Man and Biosphere Reserve (at Adam's Peak)
Sinharaja Tropical Rain Forest (between Ratnapura and Matara)
Wilpattu National Park (northeast area of Sri Lanka)
Wirawila Bird Sanctuary (near Tissamaharama)
Ruhuna Yala National Park (near Tissamaharama)
Kumana Bird Sanctuary (part of Yala)
Minneriya National Park (near Polonnaruwa)
Kaudulla National Park (near Polonnaruwa)
Wasgomuwa National Park (near Polonnaruwa)