The 18 km long Chinnar river defines the East-West Tamil Nadu/Kerala state boundary along the northern edge of the Chinnar Wildlife Sanctuary and the southern edge of the Indira Gandhi Wildlife Sanctuary.

[1] The river first proceeds through a large shola then past the Muthuvar settlement of Olikkudi[2] at 10°19′52″N 77°08′37″E / 10.331°N 77.1435°E / 10.331; 77.1435.

2 km east it is joined from the south by the Pambar River at Koottar where a comfortable tree house accommodation is available.

[3] Here it crosses into Indira Gandhi Wildlife Sanctuary in Tamil Nadu and becomes the Amaravati River.

The western part of the Manjampatti Valley catchment basin drains into the end of the Chinnar River.