In 1981, the ocean surrounding the Poor Knights Islands was established as New Zealand's second marine reserve. The marine reserve extends for 800 metres offshore around the Poor Knights Islands, where all marine life is protected.

Beneath the waves at the Poor Knights an ocean of diving has been compressed into a relatively small area. The caves, arches, tunnels and sheer cliffs provide a great variety of habitats to explore. Visitors to the marine reserve are welcome and boating, snorkelling, scuba diving and canoeing are encouraged.