If I died here, I thought, a distinct possibility, only the fish would ever find me. Or archaeologists a few millennia down the line, after the lake bed had dried and my bones had become one with sandstone.

I had been swimming for an hour in Lake Powell, a man-made body of water that floods immense canyons in the northern Arizona wilderness. It was a course that I had a glance at on a map but had never seen up close. Now I was brushing up against canyon walls rising straight out of the water a couple of hundred feet, no place to climb out, not even cracks to hold onto. I was searching for a boat waiting for our group in the cold waters of the lake under the noonday desert sun on a cloudless day.

Trying to use landmarks to get your bearings while looking through goggles at water level is hit and miss and miss and miss. I had gone off course the previous day, swimming away from the boat for 10 or 15 minutes, only to see other swimmers on the right track and hear shouts echoing across the dead-still water. Others had veered far off course, nerve-racking detours, easy to do when you have no sense of perspective. What looks like a nearby rock where you might climb out for some relief turns out to be a mile off, or two. A speck that you are sure is your boat turns out to be a buoy. You can’t even be sure when you look out where water ends and rock begins, for with the blinding glare, Lake Powell is the world’s largest reflecting pool, a liquid hall of mirrors.

The skin on my neck was searing but my extremities were numb in the 66-degree water. Not wearing a wetsuit had put me at risk of both sunstroke and hypothermia. I had no idea at what point I wouldn’t be able to go on but I could feel it coming.

And then, at a distance of a half-mile or so, I saw a not-so-small breach in the water surface: huge arms windmilling the backstroke. Martin Strel had rolled over to his back and was looking up at the canyon walls, spotting an eagle’s nest perched a hundred feet out of the water. While I was preparing to meet my maker, the leader of our gruelling open-water swim was sightseeing, communing with nature. It might have been a mirage, the sun making me delirious, but it was at least hope — it required faith and it represented all I had to work with. I swam to it and emptied my mind. I tried to keep him in sight, not letting him pull too far away.

I don’t know how many minutes passed, but when I made it to the boat, Strel reached down to pull me out of the water. He was wearing a souvenir-shop sombrero and an amused look. “Is beautiful, yes?” he said.

“A terrible beauty, yes,” I panted. I grabbed a blanket even though it was in the mid 90s and shivered under it uncontrollably for two hours.

At the past two Summer Olympics, the bandwidth almost crashed with all the hyperbole about Michael Phelps: the quote-unquote greatest swimmer ever. I was galled. If it had been Phelps out ahead of me in the waters of Lake Powell all hope would have been lost. He would have sprinted off toward the nearest television camera and then flashed his signature goofy smile, reinforcing the futility of my going on, not the possibility.

So let’s start with the obvious: Martin Strel is the world’s greatest athlete, the greatest of all time.

The Slovenian once jumped into the Danube, swam for 80 straight hours, and emerged from the waters having covered 313 miles (501 kilometres) using nothing more than the Australian crawl and a wild, flailing stroke of his own invention that he manages unconsciously for a few minutes at a time. Yes, Strel can swim in his sleep. By comparison, Phelps, in the water for just a couple of minutes at a time, is not a swimmer so much as a bather. Phelps breaks records by hundredths of seconds, Strel by hundreds of miles.

For others, an entry in the Guinness book of world records would be a life-defining event. In the Strel canon, those 313 miles are one line that you might miss down at the bottom of the page. Likewise, you might not catch his traversing the Strait of Gibraltar, becoming the first man to swim from Europe to Africa, a test that had claimed the lives of seven before him. Swimming the English Channel is so minor that he often has to be reminded that he did it at all, a mere afterthought.

Tasking the several-times-larger-than-life Strel with these small, wet matters is like asking Superman to help you move a refrigerator. No, his greatness has required the greatest of stages and he is trying to swim them all. Think of it as the Grand Slam of the World’s Rivers.

First, in 2000, he swam the length of the Danube, covering 1,878 miles in 58 days, setting a world record and providing a mere portent of things to come.

Two years later, he broke that record on the Mississippi, swimming from northern Minnesota to the Gulf of Mexico, 2,360 miles in 68 days, spending about 12 hours in the water each day.

In 2004, he took on the toxic waters of the Yangtze, covering 2,488 miles in 50 days, passing several floating corpses along the way. Over the last miles, Strel was ready to join the ranks of the not-quite-buried at sea, near death, his liver as black as coal. The Yangtze provided a useful tune-up for his greatest swim to date, the Amazon.

In 2007, he swam from Peru to the South Atlantic, 3,278 miles in 68 days. It is said that the Amazon is home to one-third of the animal species in the world and Strel encountered most of them up close. In fact, he maintained he was in communication with all manner of beasts and pleaded for safe passage. It mostly worked. He avoided the candiru, the infamous, pitiless creature that crawls up its victim’s penis and then shoots out bony spines. He managed to swim past crocodiles that lined the shores in shallow waters. He escaped bull sharks, a subspecies of the predator believed to have claimed more lives than any of God’s beasts. Strel wasn’t able to dodge all the predators, however. He believes parasites burrowed into his brain. He brought home to Slovenia a souvenir he’ll never lose, an eight-inch gash across his back where piranhas bit through his wetsuit. It is a half-inch deep. He didn’t bother to get it stitched.

According to his passport, Strel was 52 when he climbed out of the Amazon. A half-decade has passed and he estimates that he is “currently 35 years old, maybe 36.”

I was certifiably 56 when I drove past the Grand Canyon on my way to the last of four swim expeditions Strel was leading on Lake Powell last year. I have yet to dip a toe in the world’s mighty rivers but I have spent hundreds of hours in swimming pools hither and yon over the past four years, training up to two hours a day just to stave off middle-age decrepitude, and since the spring intensifying to prepare to swim with or at least within sight of Strel. And, more to the point, to damply cavort with others — let’s call them the Strelians — who understand that he’s the greatest athlete of all time and are, like me, in his thrall.

Most Strelians happen to spend a significant portion of their lives in the water and thus appreciate the river swims in a way that the landlocked and ground-bound cannot. What Strelians understand is that the aerobic demands and calories burned in a mile in the water work out to about four miles on a treadmill. Now, granted, Strel’s 313 miles down the Danube weren’t quite the equivalent of a 1,200-mile run because he had the benefit of the river’s current. But a 600-mile run, well, maybe. Whatever the case, it would have to take a prodigious toll on the body.

This was my first time among Strel’s disciples and our Lake Powell baptisms lasted two hours daily, something along the lines of a half-marathon a day, three days in a row. A few tourists filled out our roster, swimming only small segments of the course, but four of us were there to, as my significant other put it, “drink Martin Strel’s Kool-Aid.” By my side were: “Harry Potter,” a very nervous British journalist in his twenties who bore an uncanny resemblance to Daniel Radcliffe; Beth, a Floridian who worked as a physical therapist for college swim teams years before taking up the sport; and Elias, a Montreal artist and self-styled man of the world who has gone with Strel on several tours in Europe and, frankly, aspires to be Martin Strel, a real stretch as he only does the breaststroke. The fellow with at least some of the genetic stuff to follow in Strel’s footsteps is his son Borut, who hopped into Lake Powell occasionally but focused on the logistics of the tour, as he does all his father’s affairs.

I’ll admit that, at times, my faith was tested and found wanting. The pasta that Strel prepared served its purpose in our exhaustion — tastelessly, I thought — yet Beth enthused about it like it came from a kitchen awarded three stars by Michelin. Strel sat disciples down to tell them their fortunes, using a Ouija-like device, something he brings out frequently to make daily plans, life decisions and bold predictions. I was amused by the fortune-telling at first but then realized later how seriously others took it; one woman’s eyes reddened when Strel told her that a boyfriend didn’t have good intentions.

Strel didn’t use the board to predict the weather before we ventured out onto the lake in the morning. He doesn’t see the need, because he believes he can determine the weather by the force of his will and the power of his mind. That it ever rains is simply him remembering the plants must be watered and rivers fed.

When you meet Strel for the first time, your instinct is to race to his aid and pry off the giant mollusk gnawing at his face. It is, however, not a shellfish but a magnificent mass of misshapen bone and cartilage that is his thrice-broken nose, which provides him a serviceable rudder. It sits approximately in the middle of a head as large as the Incredible Hulk’s when at its deepest green.

Beneath that you find a torso as shapely as a manatee. Strel stands five-feet-11 and has a curb weight of 240 pounds. Using the BMI scale, he’s clinically obese. He has hands as big as Zdeno Chara’s hockey gloves and the wingspan of a condor. His hairless torso is something like the hull of a barge. When he moves shirtless around the boat, you sometimes think you’re being watched and later realize all that’s staring at you are nipples that would choke weaning calves. His 34 per cent body fat is entirely strategic, keeping him buoyant and warm when he’s swimming in mid-winter waters almost icing over. He works hard to maintain his girth, his diet consisting of 75 per cent carbohydrates, eating a family-sized portion of pasta with meals the way an average guy would have a dinner roll.

This less-than-textbook body only makes the beauty of the great man’s stroke all the more remarkable. His elbow position, reach and pull are exercises in perfect physics, his imperfect physique notwithstanding. For Strelians, watching Strel travel through the water at alarming speed is like watching the NBA slam dunk contest won on a 360-windmill number performed by Jonah Hill in his early, funny period.

And, of course, since this is not being written in memoriam, he is a medical marvel.

When Strel was featured on National Geographic’s The Great American Manhunt, a forensics-focused reality show, his blood test showed the presence of two separate strains of malaria, a marker for partial immunity to the disease. He also tested positive for schistosomiasis, a chronic organ-destroying disease carried by snails in river waters he swam and not something he contracted from a serving of escargot. Counting the piranha attack, Strel could have died four times already.

His mind was also subject to clinical dissection on the same show. Without knowing Strel’s identity, clinical psychologist Dr. Dan Shapiro of Penn State University studied the results of the great man’s personality test and surmised that the fellow checking off the boxes is “incredibly independent [and] absurdly confident,” strikes “people who don’t agree with him as arrogant,” engages in “magical thinking” and is “visionary or… delusional.”

Four for four.

Those who have paddled kayaks alongside Strel are accustomed to hearing him gurgle in mid-stroke with his head buried in the water. This is Strel talking to himself underwater. “I tell stories for myself to make time go,” he says. And when those paddling with Strel see him stroking away, he can be somewhere else. “I go outside [of my] body,” he says. “I go forwards or backwards in time. Or I just go away.”

Those who serve as Strel’s crew can be forgiven if they at times wish that he would just swim off into a reality separate and distant from their own. Strel can be imperious, even tyrannical on his river quest or in something as everyday as our tour. He had little time for crew members sickened and unable to fulfill their duties on the Amazon swim. He wouldn’t have fed them to the crocodiles but he did vent at them, thinking that, if they weren’t malingering, they couldn’t have been as sick as he was. Mutiny was averted only by Borut’s intervention, his diplomacy and compassion matching his father’s endurance and perfectionism. “Imagine a boat that sleeps four or six and there are more than 20 people on it for months with no relief and with everyone sick,” Borut says. “There are going to be difficult times.”

Personalities even clashed on the placid waters of Lake Powell. When we went into Cathedral Canyon, a crease in the rock that goes on for miles, only as wide as a parking spot for a Smart car, we had to cut the engine and use the walls to push our boat down with only inches on either side. “We can’t go any further,” said our skipper, Rusty, a veteran of decades on the lake, fearing damage to his boat and the prospect of being stranded. Strel, who only saw Lake Powell for the first time this year, obstinately pushed on until we were wedged in a stone crevice between walls that rose hundreds of feet.

If there is a word in Slovenian for “can’t,” Martin Strel doesn’t know it.

Fittingly, a character so large should have not one story of his origin, but three. No. 1: “Newspaper comes day when President Kennedy is shot and back page has story of Slovenian swimmer.” No. 2: “I love to swim as child, 10 years old, and my father bets three soldiers I can swim farther than them [for] a case of beer. Beer very hard to get in our country then [the former Yugoslavia]. Wine cheap, not beer. And so I swam many times across the lake until soldiers stop. My father very happy.” No. 3: “I am gymnast in school and I have a problem with coach. Coach of swimming tells me to come with him. He says, ‘You are made for swimming.’”

Despite this early encouragement, Strel fell out of the sport for long stretches. He was a soldier in the Slovenian army who distinguished himself with 37 desertions. He then became a professional gambler. In his thirties, he taught music and established himself as Slovenia’s foremost flamenco guitarist. And then, in his forties, he found a niche previously unfilled: crusading river swimmer, a marine Don Quixote. “I hear water call and I go back,” he says.

When the Amazon called, Strel became not just a name in the record book but, depending on your viewpoint, a minor celebrity or cult leader. This can be attributed to Big River Man, an award-winning documentary filmed over the course of Strel’s swim across South America. The movie scotched the doubts of those who questioned the legitimacy of Strel’s many odysseys but it remains a touchy subject among the Strelians. “The documentary doesn’t really do him justice,” Beth said. “It’s unfair.”

I concur. Big River Man shows Strel as a cartoon figure, downing whole bottles of wine while treading water during breaks in his exertions. In trailers for the movie, he was portrayed as an alcoholic. In my time with Strel on this excursion and on his frequent trips to Toronto, where he has friends, I have never seen him drink more than a glass of wine or a beer in a restaurant or bar. He does drink a bottle of wine each day on top of that but it’s wine he makes himself and it has an alcohol concentration of less than one percent. It is slightly more potent than Welchade. He attributes his endurance to the concoction.

Unfair as Big River Man was, it went a long way to raising Strel’s profile, just not as much as he had hoped or, at least, not as much as the filmmakers thought he hoped. Playing it for pathos, they made it seem that, if the Amazon swim had not been entirely for naught, it hadn’t garnered him the fame and fortune he deserved. Again, among Strelians, this is a sore point. To a crusader, success isn’t box office and a seat next to Letterman. That’s why Strel is a transcendent figure, at least among his number. Others can have their Q ratings; he has his causes. “I want to make people aware of the water, pollution, because if we do not have water, the world cannot go on,” Strel says. “The great rivers are in danger. In the Amazon it is the rainforest. Lake Powell, people use so much water, 20 or 50 years it disappears.”

Strel says he also swims for “world peace.” If the world were populated by several billion Martin Strels it would be a better place and a helluva reality show. The world has to settle for just one, but it’s enough for me.

The definition of minor heart surgery is heart surgery that someone else has. I had been wheeled out the door after surgeons rooted about my chest cavity one day in 2008 and, a little more than 24 hours later, against doctor’s orders, I went to a screening of Big River Man at a documentary festival. Though I could not stand up straight, draw a deep breath or move any faster than a shuffle, I figured I was working on borrowed time, so better make the most of it. I knew nothing of Strel before that night. Any sort of despair or resignation or fatalism washed away by the end of the film. That I would one day swim with him seemed a possibility as remote as swimming the Amazon upstream. Say what you will about me; I can brush it off. Don’t take Martin’s Strel’s name in vain, though. OK, he’s not your typical hero. Still, he inspired me and showed me that with belief and an empty mind you can do, well, if not great things, some really weird shit.

I’m on the boat wrapped in a blanket with teeth chattering, skin bubbling and lips blistering and swelling. Strel tells Harry Potter to “come to Slovenia, Lake Bled, two degrees, I make man of you.” Then Strel shakes Harry so hard that he almost coughs up his Adam’s apple. Beth says to no one in particular that Lake Powell “is the best time of my life.”

Strel does a head count. All are accounted for but one, Elias the artist, who, to find his inner Strel, has decided to breaststroke off course and into the most dangerous waters on Lake Powell, the lanes where cigarette boats speed by at 100 mph. To heighten risks, Elias decided to forego the Day-Glo swim caps so that he could better tan his shaven pate. At the speed of those boats and with the fury of their motors, the skippers wouldn’t see him in time to change course and might not even feel him if they rolled over him.

While we cruise about looking for Elias, I ask Strel what challenges await him now that he has checked the Amazon off his bucket list. He is looking through his binoculars like he can see the future. “Many things,” he says. “They ask about Ganges, most polluted river in the world. It is almost certain death. I want to do St. Lawrence but deal falls through. We talk about the Mackenzie, cold water swim. I go for cause of Eskimo people. It takes years to recover from these swims. Many years for the Amazon, but now I am ready.”

He does not mention the swim that is atop his list, the biggest river that is out there for the Big River Man.

Strel says he migrated to Arizona because of the weather and the low cost, but more than he either knows or is ready to admit, he’s physically and geographically drawn to the Colorado River. He needs a worthy stage and can only find it in the U.S. Yes, he has already swum down the definitive American river, the Mississippi, as if he were dragging Huck and Tom to freedom. But the Mississippi flows languid while the Colorado is spectacularly unruly, thus truly American. If you want to go down its white waters in a raft, you have to sign a waiver providing licensed operators with contact info for next of kin. Strel knows that he’ll be madly buffeted in the Colorado’s rapids, that he’ll bounce off rocks, that different times he’ll be sucked down into a whirlpool and have to find a way to emerge from the vortex. Borut knows not to try to dissuade his father. “He needs to do big things to feel alive and he believes he can do anything if he puts his mind to it.”

At present, the only challenge he would find impossible is the one that managers of federal lands don’t allow him to start. Though he has managed to swim portions of it, the most dangerous sections are closed off to the public. “It is difficult to get permits, very,” he says. “They say, ‘You can’t.’”

Strel can and will. He will erode the officials’ resistance like the Colorado has carved through rock on its way to the ocean. It might take years but Strel is immune to the ravages of age, at least in his own mind, which is the only thing that counts. When he does dive into that water, he might only be 31, maybe 32 years old. That swim will be an elemental story, one about a fierce force of nature and awesome power. It will be a fight for survival. I am reasonably confident that, in this ultimate test, the Colorado River should survive Martin Strel.

This story was originally published in 2013.