New Zealand is a microcontinent.
A microcontinent is a landmass that is bigger than a typical island, but smaller than a typical continent. Microcontinents usually break off of a larger “parent continent.” In the case of New Zealand, the country’s two main islands are the above-sea-level part of Zealandia, a submerged microcontinent about half the size of Australia. Zealandia broke off from Antarctica about 100 million years ago and from Australia about 80 million years ago. Today the country lies at the abrasive juncture of two of the world’s great tectonic plates, the Indo-Australian Plate and the Pacific Plate. Because these plates actively rub against each other, New Zealand has many natural hot springs, as well as occasional volcanic eruptions.