Opawa River is the name of two separate rivers in the South Island of New Zealand.

Opawa River, Marlborough

The northern Opawa River is in the Marlborough region. It flows through the town of Blenheim, and flows into Cook Strait at Cloudy Bay, just south of the mouth of the Wairau River.

Opawa River, Canterbury

The southern Opawa River is a small river in the south of Canterbury. It flows into the Tengawai River, which is itself a tributary of the Opihi River. It is located south of the town of Fairlie.