Has this tired old world been explored-out? Not Down Under, where uncharted, bottomless slot canyons hide just west of Sydney.

By Mark Jenkins

Mark Jenkins

First descent: Rick Jamieson in Orongo Canyon

"Maybe one of 'em was injured," said Rick, sitting up front in the passenger seat. "Hit by falling rock."

"There's to be an inquest," said Derek, the driver. "And autopsies."

Three days earlier, on June 14, the accident had managed to momentarily push pre-Olympic hyperbole off the front page of The Sydney Morning Herald: "Two experienced abseilers froze to death in a wilderness waterfall in the Blue Mountains after their ropes became entangled," the story reported, "leaving them trapped and dangling against a steep escarpment as night set in." The article went on to thinly outline a three-day canyoning adventure that had been advertised on the Web site of the Newcastle University Mountaineering Club as a trip with "more abseils than you can poke a piton at." The story was accompanied by a large color photograph of choppers hovering against a cliff face above a green forest, like dragonflies above a garden.

"They died on Corra Beanga Falls," said Derek, turning off onto a narrow dirt road. "You've done that, haven't you Rick?"

"That'n. Yes, I 'ave."

At last count, Rick Jamieson, 59, had descended some 200 canyons in the Blue Mountains of Australia. He wrote the book on canyoning Down Under, Canyons Near Sydney, now in its third edition. He made his first technical descent in 1961, two decades before canyoneering, or canyoning, took off as a popular sport in the deserts of the western United States. A big rock of a man—thick in the hands and feet, with curly gray hair, a grizzled beard, a heavy Aussie accent, and an uncanny resemblance to the late British explorer-mountaineer Bill Tilman—Rick tended to think more than he spoke.

Derek Cannon is Rick's partner. They've done most of the canyons in his guidebook together. Derek, 62, is a retired limnologist who worked for the Sydney Water Authority for 33 years while simultaneously rising from private to lieutenant colonel in the Australian army reserve. He's trim, indefatigable, and has led trekking expeditions around the world.

Derek and Rick go canyoning 40-plus weekends a year. We were driving to Bennett Gully, a small, virtually unknown slot canyon that had never been descended. Bouncing in the backseat of Derek's four-wheeler, I kept brooding about the two canyoneers, killed by hypothermia.

"They must not really have been experienced," I said.

Derek held the wheel steady and glanced at me over his shoulder. Rick didn't look back.

"They must have made stupid mistakes," I said.

"Or," Rick said, shrugging his shoulders, "they might 'ave just made a simple error in judgment."