It is the only river (so named) on the island — the island's other watercourses all having names ending is "stream".

The Wairahi flows generally west, roughly paralleling the island's long southwestern shore, from its origins north of Whangaparapara Harbour.

A walking track from Whangaparapara to Port Fitzroy follows the river for part of its length.

"Place name detail: Wairahi River".

This article about a river in the Auckland Region is a stub.