- Ponnaiyar River is the South Pennar River that originates in the Nandi Hills in the Chikkaballapura district of Karnataka.
- It is also known as Dakshina Pinakini in Kannada and Thenpennai in Tamil.
- It is one of the east-flowing peninsular rivers in India, like Godavari and Krishna.
- It flows through Tamil Nadu before emptying into the Bay of Bengal.
- It covers a small area in the state of Tamil Nadu, Karnataka, and Andhra Pradesh.
- The Basin is bounded on the North -West, and South by various ranges of the Eastern Ghats like the Velikonda Range, the Nagari Hills, the Javadu Hills, the Shevaroy Hills, the Chitteri Hills, and the Kalrayan Hills, and in the East by the Bay of Bengal.
- The Krishnagiri Dam and Sathanur Dam are also built across this river.
- Moongilthuraipattu Sugar Factory is situated on the bank of the river.