Wainui is a Māori language term (wai meaning water, and nui meaning large, expansive) and the umbrella entity for the three local iwi gives a meaning of "where the tidal flow leaves a big expanse of bay empty".

[1] The Wainui River flows north through Abel Tasman National Park from its sources on the slopes of Mount Evans to reach the small Wainui Bay, an indentation close to the eastern end of Golden Bay.

The sources of Wainui River near Wainui Saddle are close to the Abel Tasman Inland Track.

[2] Almost all of Wainui River's course is through dense native bush, with the lower half meandering through a narrow gorge where the river eventually flows over the 20 metres (66 ft) tall Wainui Falls, one of the most accessible waterfalls in the Tasman region.

This article about a river in the Tasman District is a stub.