The Bunda Cliffs stretch for 210 kilometres along the northern shore of the Great Australian Bight, from the Head of the Bight in the east toward Eucla near the Western Australian border. For a continuous 160 kilometres the cliff line never breaks, which gives the Bunda its grandest claim: the longest uninterrupted line of sea cliffs on Earth. Standing at the rope barrier near the Nullarbor Roadhouse, the scale is dizzying. There is no foreground, no slope, no transition. The flat plain is at your feet, and then there is air, and far below, the white churn of the ocean. The cliffs are bounded inland by the arid plain and offshore by nothing at all for thousands of kilometres. Few places on the planet feel so much like standing at the literal end of the land.

The cliffs are made of fossiliferous limestone laid down during the Cenozoic era, the rock of the Eucla Basin, built grain by grain from the shells and skeletons of sea creatures over millions of years. They are the eastern face of the Great Southern Scarp, an 820-kilometre formation that arcs across the basin. Look closely at the cliff face and the layers read like pages: bands of cream and ochre and rust, each a chapter of an ancient seabed now lifted into daylight. The sea is still at work. High-energy waves driven up from the Southern Ocean hammer the base of the wall, undercutting it, so that the whole cliff line is slowly receding northward, surrendering itself to the water one collapse at a time. The edge you stand on today is not where the edge stood a thousand years ago, and not where it will stand a thousand years from now.

From May to October, the waters below the eastern cliffs become a nursery. Southern right whales, hunted nearly to extinction in the whaling years, return to the sheltered shallows at the Head of the Bight to calve and to court. From the clifftop viewing platforms there, the spectacle can be staggering: in the peak of July and August, more than a hundred whales may be visible at once, mothers and calves rolling and breaching in water so clear their full bodies show through it. These are the same animals that, after their season here, swim south to feed in the Antarctic; in the Bight they fast, living off their reserves while the calves grow strong. To watch them from the top of a hundred-metre cliff, the wind pushing in off the ocean, is one of the great wildlife encounters of the Australian coast.

This is not empty country, whatever the emptiness suggests. The cliffs and the plain behind them are the traditional lands of the Mirning people, the coastal Aboriginal nation whose name means to listen, learn and observe, and much of the coast now falls within layered protections: the Nullarbor Wilderness Protection Area, the Yalata Indigenous Protected Area over the eastern cliffs, Eucla National Park at the western end, and the Far West Coast Marine Park in the waters below. The name Bunda Cliffs itself was formally gazetted by the South Australian government in 2014, applied to the sanctuary zone running from the state border to the Head of the Bight. The Eyre Highway, the lifeline that links the two coasts of the continent, runs within sight of this drama, and travellers crossing the long, flat miles of the Nullarbor pull off at the marked lookouts to stand, briefly, at the edge of the world.