The Sanctuary consists of catchment areas of tributaries of Kallada River upstream of the Parappar dam in Kerala. It extents over 100 square kilometres. The Sanctuary got its name from the tree Chenkurinji, which is mostly found in this area.

Besides, one of the major rivers that flows through the area is called Chenduruny (Chenthuruny). The river rises from the Alwarkurichi peak, the highest point in the Sanctuary (1550 metres), and much of its course is now covered by the reservoir.

You can visit the Sanctuary by boat from Thenmala. A battery powered van will take you to the boarding point from the information centre of Thenmala Ecotourism Project. Trekking  is allowed in some parts of the buffer area.

This Sanctuary has animals such as the bonnet monkey, lion tailed monkey, Nilgiri langur, squirrels, Indian bison, sambar deer, barking deer, mouse deer, Indian elephant and wild boar (full list). There are more than a hundred species of birds in the sanctuary. However, few could be seen during a boat trip. (Picture on the left shows a sapling of Chenkurunji). The Sancturay is part of  Agastyamalai Biosphere Reserve.