Sea levels began to rise 7,000 years ago, after which the islands separated from the rest of New Zealand.

[citation needed] Originally owned by the Māori Ngā Puhi iwi, they were sold to the New Zealand Government in 1883.

The islands have been identified as an Important Bird Area, by BirdLife International because they are home to a breeding population of about 500 pairs of Pycroft's petrels.

Hen Island, or Māori: Taranga, lies 7 kilometres (4.3 mi) to the southwest from the rest of the archipelago.

A remnant of a four-million-year-old volcano, the island is dominated by a rocky ridge reaching to about 417 metres (1,368 ft) at its highest point, called The Pinnacles.

Sail Rock, a stack, rises from the ocean 3 kilometres (1.9 mi) to the south of Hen Island,[10] and is a prominent navigational point for yachts.

The once common species of forest bird found in the North Island, was nearly wiped out by the human introduction of mammalian predators, such as rats and stoats.

[14] The New Zealand Department of Conservation and the Ngati Wai iwi have entered into partnership to set up a sanctuary for the Polynesian rat, or kiore, on the islands Mauitaha and Araara.