The Kōhaihai River (Māori: Kōwhaiwhai) is a river of the northwest of New Zealand's South Island. Flowing southwest and then west from the Dommett Range, the river's entire length is within the Kahurangi National Park. The river's mouth marks the south western end of the Heaphy Track and the northern terminus of the West Coast's road system. The nearest town is Karamea.

• List of rivers of New Zealand

"Place name detail: Kohaihai River". New Zealand Gazetteer. Land Information New Zealand. Retrieved 12 July 2009.