How the Poor Knights got their English name remains a minor historical puzzle. Historian John Beaglehole speculated in 1955 that the islands might have been named for the Poor Knights of Windsor, a group of military pensioners at Windsor Castle. Or, he suggested, they might have been named for their resemblance to Poor Knight's Pudding -- a bread-based dish dipped in egg and fried, popular among European sailors of the discovery era. The Maori name, Tawhiti Rahi, carries no such ambiguity. The chain sits 50 kilometers northeast of Whangarei and 22 kilometers offshore, halfway between Bream Head and Cape Brett. Two main islands -- Tawhiti Rahi at 151.5 hectares and Aorangi at 101 hectares -- anchor a constellation of smaller islets, rocky outcrops, and submarine arches.

The Ngati Wai and Ngati-Toki peoples had lived on the islands for generations, growing crops and fishing the surrounding waters. When Tatua left with his warriors to join Hongi Hika's expedition, an enslaved man named Paha escaped and traveled to Hokianga, where he found Waikato, a Hikutu chief nursing an old grievance. Years earlier, Tatua had refused to trade pigs with him. Waikato gathered his warriors, and they paddled three canoes through the night to the undefended islands. The attack was swift and devastating. Tatua's wife Oneho and their daughter were captured and taken to the mainland, where a distant relative recognized Oneho and helped the two escape. Tatua found them at Rawhiti in the Bay of Islands -- an unexpected reunion amid destruction. The islands were declared tapu, and the survivors never returned to live there.

Below the waterline, the Poor Knights are a different place entirely. The surrounding marine reserve protects subtropical species carried south by warm ocean currents, making these islands one of the premier diving destinations in the Southern Hemisphere. The volcanic cliffs plunge into deep water, creating walls encrusted with life. But the signature feature is Rikoriko Cave -- the largest sea cave by volume in the Southern Hemisphere. The cavern measures over 221,000 cubic meters, with a ceiling height of 35 meters and an opening wide enough for small tour boats to enter. Below the surface, the cave extends 26 meters deep. Boat tours depart from Tutukaka, and while no one can step ashore, the underwater and cave experiences draw divers and visitors from around the world.

The islands are what remains of a rhyolitic volcano that erupted between 10 and 9.5 million years ago, during some of the earliest activity of the Coromandel Volcanic Zone. At its peak, the volcano is estimated to have stood 1,000 meters tall with a diameter of 25 kilometers. What survives above water today is a fraction of that original mass -- eroded stumps of volcanic rock surrounded by deep ocean. The oceanography is as remarkable as the geology. Large internal tides -- subsurface waves driven by tidal flow against the continental shelf -- occur in the region, their surface signatures visible from space. These waves can reach amplitudes of 100 meters and generate flow speeds of half a meter per second, stirring nutrients from the deep and feeding the marine ecosystem that makes the Poor Knights so biologically rich.

After Maori departed, the islands existed in a kind of accidental wilderness. Feral pigs left behind on Aorangi were not exterminated until 1936. Since then, the islands have become a protected nature reserve where permits are granted almost exclusively for scientific research. The Poor Knights lily, with its spectacular red flowers, has become a popular garden plant worldwide despite growing wild only here. BirdLife International designated the islands an Important Bird Area for their population of roughly 200,000 breeding pairs of Buller's shearwaters -- a seabird that nests in the islands' volcanic soil and ranges across the Pacific. The tapu that Tatua declared in grief has, in its way, proved to be the most effective conservation measure the islands have ever known. Left alone for two centuries, they became what most protected areas aspire to be.