The Whanganui River is a major river in the North Island of New Zealand. It is the country's third-longest river, and has special status owing to its importance to the region's Māori people. In March 2017 it became the world's second natural resource to be given its own legal identity, with the rights, duties and liabilities of a legal person. The Whanganui Treaty settlement brought the longest-running litigation in New Zealand history to an end.

The North Island, also officially named Te Ika-a-Māui, is one of the two main islands of New Zealand, separated from the larger but less populous South Island by Cook Strait. With an area of 113,729 km2 (43,911 sq mi), it is the world's 14th-largest island, constituting 43% of New Zealand's land area. It has a population of 3,997,300, which is 77% of New Zealand's residents, making it the most populous island in Polynesia and the 28th-most-populous island in the world.