- From: The Sunday Times
- April 27, 2013
And it's almost as dangerous as a trip to outer space.
More than 90m below ground, divers are beneath millions of tonnes of rock. And at 6.5km long, Cocklebiddy Cave is the longest underwater passage in the country, up to several hundred metres wide, along a fault line in the biggest slab of limestone on the planet.
In 1972 and 1973, at least eight people died cave-diving in Australia, prompting the formation of the cave divers association and the introduction of a permits and a training system that has kept fatalities to two since then.
That record was almost ruined in 1988 when producer Andrew Wight led a Nullarbor cave-diving expedition and a freak storm caused the entrance to collapse, leaving 15 people trapped underground.
A rescue mission was mounted and everyone survived in a harrowing ordeal that inspired the movie Sanctum.
So mysterious are the world's giant, flooded underwater caverns, the Maya believed the entrances to them to be portals to the underworld.
"It's an unforgiving sport. You can't afford mistakes. If anything goes wrong, you have to deal with it underwater," Mr Vanderleest said.
He said the Nullarbor's six regularly dived caves were among the most popular in the country for Australia's small and highly trained group of cave divers, who number about 800, including up to 70 in WA.
Phenomenal visibility is the result of artesian basin water that has taken thousands of years to filter through the limestone surface layers, the cave divers association's scientific officer, Ian Lewis, said.
And exploring the underwater realm isn't cheap.
"A re-breather will be $12,000-$15,000, an underwater scooter $5000, but people don't mind the expense because when your life is reliant on equipment, you don't want an old VW, you want a Ferrari," Mr Vanderleest said.
Perth diver Craig Challen holds the "crown of Cocklebiddy" for going deeper than anyone to the end of the cave system, where it branches into several tight passages. Another Perth legend of the sport is Paul Hosie, who has mapped more than 15km of virgin cave-diving passages in the Nullarbor and elsewhere.
Fellow diver Geoff Paynter has tackled Cocklebiddy more than a dozen times since it was discovered in the '70s.
He said most West Australians had no idea that the treasure existed.
"People are literally driving over the top on their way to Perth or Adelaide and they don't realise what's below," he said.