Apart from about 62 species of mammals, about 320 different bird species including the Malabar Hornbill, darters, drongos and kingfishers make the sanctuary their home. 40 species of reptiles have been recorded here and 27 species of amphibians live within the sanctuary precincts. The Sanctuary is also home to a wide variety of butterflies and fishes also.

Interestingly, tourists are allowed only into a small portion of the buffer zone surrounding the lake. Strict guidelines have been set up to manage tourist flow and Eco - Development programs to include tribals in forest conservation has made this sanctuary one among the best administered sanctuaries in the country.

Every year part of the buffer zone also opens up for one of the largest pilgrimages in the country celebrated among Hindus, the pilgrimage to Sabarimala. The much worshipped shrine and temple of Lord Ayyappan rests within the sanctuary.

Park activities include two hour boat trips on the lake, guided jungle walks, the two/three day `tiger trail' full day treks into the park, three hour guided night treks into the park and full day bamboo rafting on the lake.