The Gulden Zeepaert was not exploring so much as lost, in the productive way that produced so much of the early map of Australia. Thijssen and Nuyts had no interest in this barren southern shore and no reason to linger; their business lay thousands of miles north, in the trade of the Indies. They sailed on, leaving behind more than a thousand miles of coastline drawn from the deck of a ship that never meant to be there – one of the longest single stretches of the continent any European had yet set down on paper. Nearly two centuries later, in 1802, Matthew Flinders arrived in HMS Investigator to chart the same waters in earnest, anchoring in nearby Fowlers Bay and naming the whole island group after Nuyts. The Dutch had glimpsed the place; the British measured it. St Francis itself sits second in size among these islands, around eight hundred hectares of low ground, smaller only than neighbouring St Peter.

Stand on St Francis at dusk in summer and the sky fills. This is one of the great seabird islands of the southern coast, home to something like a quarter of a million pairs of short-tailed shearwaters – the muttonbird, that astonishing ocean wanderer that migrates each year to the North Pacific and back. The island supports more than one percent of the world's population of these birds, along with white-faced storm-petrels and pied oystercatchers, enough to mark it as an Important Bird Area of global significance. Australian sea lions haul out on its rocks, and little penguins shelter in its burrows. For creatures that need a place free of foxes and cats and people, the island's remoteness is its great gift.

Like many of these islands, St Francis was once put to work. A century or so ago it served as a base for sheep grazing, the hardy stock left to fend for themselves on a heath of saltbush and low shrub far from the mainland; at times the island is thought to have had a hand in the whaling trade as well. Those days are gone. The island now lies within the Nuyts Archipelago Wilderness Protection Area, with the surrounding sea protected as a marine park – close to the highest level of safeguard the state can offer. The grazing leases have given way to a single purpose: leaving the place alone. What was once a remote outpost of agriculture is now a remote outpost of wildness, which on this coast amounts to the same lonely horizon, differently valued.

St Francis does not stand alone. It anchors a whole scattered fleet of islands – the Nuyts Archipelago – strewn across the sea off Ceduna, each a fragment of higher ground left behind when the oceans rose at the end of the last ice age and drowned the plains between them. St Peter Island, larger still, lies nearby; smaller rocks and islets trail off in every direction. What they share is isolation, and isolation here is a form of mercy. Cut off from the foxes, cats and rabbits that have hollowed out so much mainland wildlife, these islands have become arks – places where sea lions can pup, where shearwaters and storm-petrels can burrow and breed in their millions, where the original cast of the southern coast still plays out largely as it did before European ships first nosed along this shore. The same remoteness that once made the islands hard to farm is exactly what makes them worth protecting now.