Cocklebiddy Cave is a single passage, mostly submerged, that bores away from a sinkhole entrance into blackness. Around ninety percent of it lies underwater, reachable only by cave divers willing to swim hundreds of metres from daylight with no easy way back. In September 1983 a French team laid line deep into the third flooded chamber and claimed the world record for the longest cave dive. Two months later an Australian expedition led by Ron Allum, with Hugh Morrison pushing the far line, swam past the French marker and extended the record to roughly 6.24 kilometres of penetration from the surface. South Australian diver Christopher Brown nudged it another twenty metres in 1995. Each advance was measured in metres, won at the limit of human endurance.

In late 2008 a team returned to map the cave's most distant reaches using rebreathers, which recycle a diver's breath to allow far longer dives, and radio-location "pingers" devised by Ken Smith to fix their position through solid rock. Two of those explorers were Craig Challen, a Western Australian, and Richard Harris, a South Australian. A decade later their names travelled the world. In 2018 the pair joined the rescue of a youth football team trapped deep inside Thailand's flooded Tham Luang cave, sedating and guiding the boys out one by one through water that had already killed a rescuer. They were jointly named Australians of the Year in 2019. The skills that saved those children were honed in places exactly like the dark water under Cocklebiddy.

Water has always set the terms of life out here. Cocklebiddy began as an Aboriginal mission station, and today only stone foundations remain to mark it. During World War II, army engineers came hoping the local lakes might supply fresh water, but the ground played a cruel trick: a thin skin of fresh water floated atop a vast reservoir of brine, and the dream of a desert oasis dissolved into salt. The surrounding country is rich in its own quiet way. Twenty kilometres to the south-west, botanists found a plant new to science, the tussock-like Harperia eyreana, formally described in 2000. The Nullarbor only looks empty to people in a hurry.

Cocklebiddy keeps a time almost nobody else uses. Along this isolated strip of the Eyre Highway, communities set their watches to UTC+8:45, an unofficial "Central Western" zone wedged forty-five minutes ahead of the rest of Western Australia. There is no law behind it, only the practical logic of people living far from anywhere who decided the standard clock did not suit a sunrise this far east. The nearest coast, Twilight Cove, lies twenty-six kilometres south, where the limestone plain breaks off in cliffs above the Southern Ocean. In 2007 the Australian comedy duo Hamish and Andy rolled through, briefly putting this speck on the national map. Then the highway emptied again, the way it always does.