WE WERE DISCUSSING the accident again, trying to figure out how it could have happened. It was early morning, and though the highway was striped with sunlight, the bush was as black as ever.

“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.”

GEOGRAPHY IS destiny. Australia's Blue Mountains are ideal for canyoning because they aren't, in fact, mountains at all, but rather a long sandstone plateau riven with gorges—an incised geography of 500-foot cliffs, steep talus, and crayfish creeks camouflaged and shrouded beneath gorgeous, pale-skinned blue gum trees, ferns the size of Parisian fountains, fens of eight-foot razor grass, and shawls of green moss on every stone and steep wall. Imagine a bony Utah landscape with Louisiana foliage masking slot canyons beneath a python's nest of roots. Indeed, most slot canyons here don't show up on maps, and Rick declared that topos are “nearly useless” in canyoning.

The Blues rise like a distant wave just west of Sydney. Sydney: the beach-blond antipodal sister of San Francisco, with a better port, a bigger gay-pride parade, cleaner streets, swimable seas, a week of sun for every day of rain, and bragging rights as this year's host of that time-honored TV spectacle, the Olympics.

Instead of spectating in September, I flew to Australia in June, three months before the crowds, to go out exploring with old, gnarly, unsponsored athletes whose sport won't ever be in the Olympics.

But June in Australia is winter. Canyoning is rarely done in winter. Indeed, I'd been told by an American canyoneer that it would be impossible to go canyoning in June: “You'll freeze to death.” When I mentioned this to Rick in our first phone call, he said something that sounded like “aaarrrgh,” then grumbled about “bloody whingey Americans.” I liked him already.

The morning Rick turned up to drive me out to do our first canyon (Derek was busy that day), it was snowing in the Snowy Mountains, south of the capital, and newscasters were calling the weather “bittah cold.” The city people were hiding under winter coats and wool scarves, and Rick was wearing exactly what you'd expect of a man whom one local canyoneer described as a “fokkin legend”: ratty sweater, threadbare khaki shorts, flattened sneakers.

Rick is one of those old-school bush veterans who lives in shorts. Long pants are as much an anathema to him as they would be to a rugby player. So too a coat of any kind. “The best plan is to wear a woolen jumper next to the skin,” he writes in Canyons Near Sydney. Same goes for the misery of heavy hiking boots: “We recommend Volley sandshoes [cheap canvas sneakers], as they are quite good on slippery rocks.”

Brushing aside the beer cans in the back of his station wagon, I saw that his pack was no better: a potato-shaped lump suffering from such great age and abuse that all the buckles were gone and the once-shiny nylon fabric had been worn to fuzz. Crammed in with the rest of his gear and supplies was a dark, unidentifiable object.

“What's that?”

“Whut? Me wetsuit?”

Although still vaguely blue, it resembled some ragged animal skin, with the sleeves cut off at the biceps and legs cut off above the thighs. Most appalling, the crotch was ripped from belly button to tailbone.

“That keeps you warm?”

“Nah,” said Rick sheepishly. “Caun't say that it does. But I brought me balaclava.”

I took all this as a good sign. The older the gear, the better. People with new gear scare me: The scanty wear-and-tear of their equipage is too often indicative of the scantiness of their experience, which means you might not want to go on a tough hike with them, let alone descend into the orifices of the earth.

That day we did a canyon called Yileen, an Aborigine word for “dream.” It had numerous rappels that dropped straight into icy ebony pools.

“There go me family jewels!” Rick would howl, and then rapidly half-wade, half-swim down the penumbral corridor and stumble up onto the next sandbank, laughing. I was wearing an intact wetsuit and it was still bone-chilling.

By the time we got to the final rap, a stunning 200-foot drop alongside a vaporous waterfall, our feet were wooden blocks and our fingers rubber bananas. It took an hour of hiking fast and hard uphill with packs to warm up. Rick declared the day “a beauty.”

One good measure of an adventurer is how he acts when he is uncomfortable. Does he whine, keep quiet, or revel? The first is unforgivable, the second acceptable, the last always admirable.

That night we sat close to the woodstove in Rick's home at the edge of the Blue Mountains and drank hot tea, and after some prodding Rick told me about a 950-mile canoe trip he made down the Mackenzie River right after getting his Ph.D. in electrical engineering and marrying Jane (pronounced “yana”), his Danish wife. That somehow led to another adventure that he inexplicably referred to as “the fahs.”

“Fahs?” I said.

“Yap. FARCE: Fantastical Australian Round-the-World Climbing Expedition. 1972. Six months. Drove a combi from Denmark to Australia, right through bloody Asia.” He stretched his muscled legs, which, if it weren't for the lumps and scars and half-century tan, could belong to an Olympic runner. “Wanted to climb a mountain in Afghanistan, an' almost did.”

YILEEN WAS JUST a warm-up, a chance for Rick to see if I could cut the mustard.

“Got one!” he said one morning, as if snatching a trout from a stream. “Canyon's called Oronga.” Which inaptly means “sleep” in the Aborigine language.

No one had successfully completed a descent into Oronga. Even today, in our nothing's-left-everything's-been-done world, the Blue Mountains are still not explored-out. No matter that they're a mere two-hour train ride from four million people. Five years earlier, Rick and some mates had attempted Oronga but had been turned back by a drop so deep they couldn't see the bottom.

“Was one a them misty mornin's,” Rick said, “and the stream fell over the cliff and just vanished into the clouds.”

Rick and I did Oronga, top to bottom and back to the car, in a big, eight-hour loop. It started with a short rappel through overhanging vines, followed by a rap from a limb into an abyss, a dozen passageways as dark and dank as dungeons, four consecutive long rappels down overhanging rock, and an unbelievable bushwhack out in which Rick's legs were so severely gouged and scratched that I could follow the drips of blood.

“Whut a bahgain,” Rick roared, tossing me a beer from behind the car seat.

During the hike out I learned that Rick had been a freelance computer programmer since the dawn of the damn machines. “Don't like to work more'n couple days a week.” Which left time for raising two sons and one daughter, reading voluminously, and writing books on subjects other than canyoning, including A Religion Without a God (a treatise on the faith of atheists) and Let's Spel Lojicly: Wi Stic tu the Hard Old Way ov Spelling? (an argument for the simplification of English orthography). He had also managed to lead 13 trekking expeditions to the Himalayas, climb the Matterhorn twice, and drive overland from Munich to Cape Town.

“We got ourselves into heaps of pickles in Africa. Mighty! Spent a whole month in jail in the Congo. They thought we were bloody mercenaries. Ten days in a hole in Brazzaville, and they shipped us down the big river—Pygmies would paddle out and give us bananas—to Pointe-Noire, where we spent another three weeks in jail before gettin' out. At any one time we were always in at least two pickles. Tryin' to get ourselves out of one of 'em while straightaway pullin' ourselves into another.”

THE THREE OF US stepped out of the car above Bennett Gully and looked at the map. Derek was outfitted just like Rick: wool sweater, shorts, Volleys.

Dropping into the head of the canyon, we were instantly engulfed by tunnels of vegetation, one after another, sometimes wading through the water, sometimes balancing along a latticework of deadfall suspended like a bridge above the streambed. When the brambles became impassable, we would scrabble up the canyon sidewalls and work our way along slopy, discontinuous ledges.

Slithering, clambering, and clawing through bush—literally bushwhacking—is unique to Blue Mountain canyoning. To be a good canyoneer here, you must be a great bushwalker. It was instructive to watch how gracefully Rick and Derek tiptoed along the alligator backs of giant logs, contorted through cobwebs of vines, and leapt from rock to rock. We were as efficient as guerrillas, the man in front rotating as each of us ran into vegetal cul-de-sacs and advised the two behind to find a different path. At any drop, or whenever we got rimrocked, the point man would already have a rope ready by the time the other two arrived.

We were down in the dark, passing from one chamber to the next, when suddenly, right in front of us, there was sky. A brilliant wedge of blue between two massive black walls. At our feet, the stream rushed toward a drop-off, pooled in a cleft as if psyching itself up, and then slowly slid over the edge like a suicide jumper who has second thoughts a moment too late.

We took turns stepping carefully to the lip, hanging onto a limb, and looking down. It was a tremendous drop. The rock was undercut and the stream came apart as it fell through the yawning emptiness.

A hundred feet down and to the right was a long ledge. Unfortunately, below that point we could see nothing but blank walls.

“She may not go,” said Rick. “After the ledge it's a hell of a long ways to the ground and looks like there's nothin' for abseils.”

I volunteered to check it out. Reaching the ledge required traversing a fragile trellis of branches suspended in space—something akin to crawling out onto a lilac bush drooping off the side of a 50-story building—which I managed, barely. On the ledge I hung out as far as I could in different places, searching the walls directly below. Unless I found something from which to set up another rappel, I would have to jug back up the rope and we would be forced to somehow back out of Bennett Gully.

I was about to give up when I spotted something beautiful: a dead tree. A slender, limbless, blackened trunk leaning out of a seam. I immediately rappelled down to it and attached myself. I was now two ropes below Rick and Derek.

“It'll go!” I yelled up, exhilarated.

Rick's voice was barely audible. “Will…the…ropes…reach…the…bottom?”

When you're looking straight down, it's hard to judge distance. I studied the surrounding cliff faces disappearing into the forest. Our ropes were 200 feet long. It couldn't be more than 200 feet to the bottom.

“Ye-e-e-sss….”

I wasn't sure. I thought they would reach. It was a judgment call.

“Abseiling!”

Rick and Derek rapped down to the ledge, pulled the ropes, set up the next rappel, and started down again.

The one foolproof way to get yourself killed in a canyon is to get stranded halfway. If it starts to rain, you'll either be drowned, swept over the cliffs, or die of exposure. Even if it doesn't rain, but you're wet and the temperature drops, or the wind picks up and blows the waterfall over you and you subsequently become wet, you'll be popsicled in a matter of hours.

The one foolproof way to get stuck halfway is to pull your ropes down from above, eliminating all chance of retreat, only to find that they don't reach the bottom. Unlike in mountaineering, where you can usually turn around at almost any point, serious canyoning is a one-way trip. Once you pull your ropes, the only way out, the only way back home, is down.

Derek and Rick completed their descent and again pulled the ropes. Then we were all three hanging from a small dead tree on a remote cliff-face in the middle of the Blue Mountains. We knotted the ropes through the sling around the tree and dropped them.

They dove down through space, and stopped. They didn't reach. I couldn't believe it. We could see the ends dangling in midair, snapping lazily like tiger tails, the forest floor still somewhere far below.

“They're really close,” I said.

“Fair dinkum,” said Rick. “We get down there and we'll be laughin'.”

Derek chuckled.

“You have the extra short rope, right, Rick?” I was trying to sound imperturbable. They knew what I was about to suggest: tie the short rope permanently to our dead tree, put a loop in the end, and hang the long ropes through the loop. It would require a midwall transfer from the fixed rope to the double, a dangerous maneuver at best, but it would give us an extra 30 feet or more.

“Tricky,” said Rick, obviously pleased.

“If it doesn't reach—” Derek shrugged and didn't finish his sentence.

We rerigged the ropes, and I went first. Down the single line, making the transfer onto the double; then came a great swing out into midair several hundred feet above the earth, something that always gives one a minor synaptic shock. As I slid down the ropes, 15 feet out from the overhanging wall, I still couldn't tell if they reached the ground. Near the bottom the ends were coiled in the top of a tree. I anxiously descended through the tree to the very end of the rope. I was ten feet from the ground.

Close enough. I dropped.

“The….ropes…reach!”

Derek let out a battle cry and swung into space.

When he reached the ground, Rick, laconic as ever, looked back up and said, “That dead tree. Won't be there for long.”

By twilight we were walking through tall grass between ghostly blue gum trees. It began to rain, and Rick and Derek start singing “April Showers,” the Al Jolson tune. Then a cold night set in and it began to pour.

Give 'Em Enough Rope