The South Island, also named Te Waipounamu in Māori, is the larger of the two major islands of New Zealand in surface area, the other being the smaller but more populous North Island. It is bordered to the north by Cook Strait, to the west by the Tasman Sea, and to the south and east by the Pacific Ocean. The South Island covers 150,437 square kilometres (58,084 sq mi), making it the world's 12th-largest island, constituting 56% of New Zealand's land area. At low altitude, it has an oceanic climate.

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.