The Pambar River originates in the Anaimudi Hills in Idukki District of Kerala. Pambar River (Sarpanadi) is a river which flows through the Sivaganga, Pudukkottai and Ramanathapuram districts of Tamil Nadu. It originates at Perunganur in Pudukkottai district and flows for about 50 kilometres before joining the Bay of Bengal at Puttukidapatnam. It joins the Tennar at Tevarendal and Virusuliar at Kidangur. The holy town of Thiruppunavayil or Thiruppunavasal is located on its banks. The Pambar formed the official boundary between the Thanjavur Maratha and Ramnad kingdoms from 1725 to 1799. Currently, it forms Pudukkottai district's boundary with Sivaganga and Ramanathapuram districts.
Pambar River traverses Turner's Valley in Eravikulam National Park and flows into the Chinnar Wildlife Sanctuary through the Taliar Valley between Kanthalloor and Marayoor Villages and eastwards through the sanctuary. The Pambar, Kabani and Bhavani are the only rivers of the 44 in Kerala that flow eastwards. It is joined by seasonal rivulets and a few perennial streams originating from sholas in the upper reaches.
The Pambar merges with the Chinnar River at Koottar where a comfortable tree house accommodation is available. The Chinnar follows the interstate boundary along the northwest edge of the sanctuary and becomes the Amaravati River in Tamil Nadu, reaches the Amaravathi Reservoir and Dam and eventually joins the Kaveri River near Karur.