The sanctuary lies in between the Anamalai hills and Nelliampathy hills. Much of the sanctuary is part of Anamalai hills with peaks up to 1,438m (Karimala Gopuram) in the southern boundary of the sanctuary, 1,120m (Vengoli malai) in the eastern boundary, 1,010m (Puliyarapadam) in the west and 1,290m (Pandaravarai peak) in the north. Nelliampathy hills that lies in the north scale down and opens up itself at a place called Thoothampara, just abutting the northern boundary of the sanctuary which provides a natural opening through the Nelliampathy hills from Anamalai hills, at an average elevation of 600m above mean sea level. From the south western perspective, where, Parambikulam Ar and Sholai Ar meet at a point where the elevation is 473m (the second lowest point in the sanctuary), to form Chalakkudy river, the sanctuary appears as a completely tilted drainage basin that drains to this point, except for a little portion in the north, where the drainage is towards east.