Gannet Island is a small island some 19 kilometres (11.8 mi) offshore from Kawhia on the west coast of New Zealand

New Zealand

New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

's North Island

North Island

The North Island is one of the two main islands of New Zealand, separated from the much less populous South Island by Cook Strait. The island is in area, making it the world's 14th-largest island...

. Protected as a wildlife sanctuary, it was found to be the country's largest single breeding colony of Australasian Gannets in a 1980 census.

The island consists of the eroded remnant of a tuff ring, erupted about half a million years ago. It is considerably younger than, and compositionally distinct from, the nearby onshore Alexandra Volcanics (Mount Karioi and Mount Pirongia

Mount Pirongia

Mount Pirongia is an extinct volcano located in the Waikato region of New Zealand's North Island. It rises to 959 metres and is the highest peak in the Waikato region. It was active in the late Pliocene and early Pleistocene times...

) and Okete Volcanics. It is located on the eastern edge of the North Taranaki Graben, rising
15 metres (49 ft) above sea level from a base about 65 metres (213 ft) deep.