Southern right whales earned their grim name from the whalers who nearly erased them. Slow swimmers that hugged the coast, rich in oil, and – conveniently for hunters – inclined to float once dead rather than sink, they were judged the "right" whale to kill. The logic was brutally practical: an animal that came close, moved slowly, and stayed on the surface afterward was the one a whaleboat could actually catch and keep. Nineteenth-century whaling stripped the southern oceans of perhaps ninety-five percent of them, and by the time hunting finally stopped, only a few thousand survived across the whole Southern Hemisphere. The sanctuary was, in effect, an act of repair. Proclaimed on 22 June 1995 under the Fisheries Act, it set aside the water these recovering animals depend on, in the place they return to most faithfully of all.

What makes this stretch of coast extraordinary is how close the whales come. The Bunda Cliffs – part of the longest uninterrupted line of sea cliffs on the planet, running more than two hundred kilometres along the edge of the Nullarbor – drop straight into the water, so a mother and her newborn calf can rest in the shallows almost directly below your feet. There is no gentle beach, no shelving approach: just deep blue ocean meeting a white limestone wall, and whales hanging in the water at its base. Females linger here for up to three and a half months, far longer than the males, nursing calves in the calm green water before the long return to the feeding grounds of the Southern Ocean. Researchers have watched this coast through photo-identification studies since 1991, learning to recognise individual whales by the rough patches of skin on their heads. In peak years they have counted well over two hundred calves born along this stretch in a single season.

The whales that crowd this coast in winter spend the rest of their year somewhere unimaginably colder and wilder. Southern right whales are creatures of the deep Southern Ocean, fattening through the summer on dense swarms of krill and tiny copepods in the freezing waters that ring Antarctica, then carrying that stored energy thousands of kilometres north to breed. A mother arriving at the Bight may not feed seriously again for months; she lives off her own blubber while she nurses, pouring the Antarctic harvest into a single growing calf. The sanctuary protects only one end of that journey – the nursery. The other end lies far beyond any boundary a government can draw, in seas no fence can reach.

Protected areas are not permanent things; they are arguments written in legislation, and the arguments change. From late 2012 the sanctuary was folded inside the broader Far West Coast Marine Park. In October 2016 the original whale sanctuary, classified at the strictest conservation level a reserve can hold, was formally abolished – its protections rolled into a redrawn system of state and Commonwealth marine parks rather than simply withdrawn. The names on the map keep being rubbed out and rewritten. And lately the population itself has begun sending worrying signals: after decades of slow recovery, the number of calves born along this coast has been sliding since 2017, a decline researchers increasingly link to a warming ocean disrupting the krill far to the south. The whales, indifferent to the paperwork, keep coming back to the same cold corner of the Bight – but in numbers that no longer only climb.