The story begins with a long voyage far off course. The Gulden Zeepaert, captained by Francois Thijssen, was bound from the Netherlands toward Asia when it ran along roughly 1,800 kilometres of Australia's southern coast in 1626-27 - a stretch no European had mapped. Aboard was Pieter Nuyts, a senior official of the Dutch East India Company, and Thijssen named St Peter Island in 1627 after Nuyts' patron saint. The neighbouring St Francis Island was charted on the same passage. The wider archipelago would not carry Nuyts' own name until 1802, when the British navigator Matthew Flinders, surveying the same coast, named the Nuyts Archipelago in honour of the Dutchman who had passed this way 175 years before. Few places in Australia layer their European history so neatly: a Dutch saint's name on the island, a Dutch diplomat's name on the group, applied by an Englishman generations later.

For a time in the 1820s and 1830s, St Peter Island drew a harder kind of visitor. Seal hunters worked these waters, part of the brutal early-colonial trade that stripped the southern coast of its fur seals with little thought for the future. Archaeologists have since found whale vertebrae on the island, physical traces of the era when this remote shore was a station for hunting the giants of the Bight. Today the St Peter Island Whaling Sites are listed on the South Australian Heritage Register as a place of archaeological significance - protected not for any beauty but as evidence of a punishing chapter in the region's past, when distant markets reached all the way to this lonely island.

Now the island belongs mostly to the birds. St Peter Island forms part of the Nuyts Archipelago Conservation Park, with the surrounding waters protected as a marine park, and BirdLife International has recognised the wider archipelago as an Important Bird Area. The reason is its colonies: the island and its neighbours support more than one percent of the world populations of short-tailed shearwaters, white-faced storm-petrels and pied oystercatchers. Each is a globally significant figure, the kind that turns a quiet island into a conservation priority. Across the narrow Yatala Channel lie the Tourville and Murat Bays, another haven for birds just west of Ceduna. Where sealers once camped, shearwaters now wheel in their thousands at dusk, returning to burrows on an island that has outlived the industries that briefly claimed it.

St Peter Island anchors the Nuyts Archipelago, a loose scatter of islands and islets strung along the coast off Ceduna. It is both the largest and the most accessible of them - and, after Kangaroo Island, the second largest island in all of South Australia, a fact that surprises visitors who expect such a long landmass to be better known. Its size and position give it weight: it shelters the approaches to the bays behind it and forms a natural counterpoint to the smaller, wilder islets of the group, several of which serve as undisturbed refuges for wildlife. From the mainland near Ceduna the island reads as a low green presence on the western horizon, a fixed point that sailors, sealers, mapmakers and now conservationists have all measured themselves against for four centuries. It is, in the truest sense, a landmark - the first of this coast to be named, and still the largest thing on the water.