- Vaigai River is the longest stream south of the Cauvery Delta.
- It entirely lies in the state of Tamil Nadu.
- It originates in Varusanadu Hills, the Periyar Plateau of the Western Ghats range.
- It flows northeast through the Kambam Valley, which lies between the Palani Hills to the north and the Varushanad Hills to the south.
- It is one of the east-flowing peninsular rivers in India, like Godavari and Krishna.
- The Vattaparai Falls are located on this river.
- The river empties into the Palk Strait near Uchipuli, close to the Pamban bridge in Ramanathapuram District.
- Its main tributaries are Suruliyaru, Mullaiyaru, Varahanadhi, Manjalaru, Kottagudi, Kridhumaal and Upparu.
- The Vaigai also receives another minor tributary namely, the Varahanadhi (Varaha River) on its left bank below the Vaigai dam.
- The Vaigai was the river that flowed through the Madurai, in Tamil Nadu.
- The river finds a mention in Sangam literature dated to 300 B.C.E.