He's been called "a hero in a Speedo", but Slovenian endurance swimmer Martin Strel looks more like your average middle-aged, pot-bellied Joe than he does an international, six-packed superstar.
But then appearances can be deceiving.
Strel has been making waves internationally ever since he ditched the world's chlorinated pools for its freshwater rivers, becoming the de-facto "Big River Man" to raise awareness of global environmental issues.
He began, in 1992, with the Slovenian Krka, which took him 28 hours to swim all 104.60km.
Since then, he has swum the full length of the Danube (3,058km), the Argentine Parana (1,931km), the Mississippi (3,862km) and the Yangtze (4,002km), the dirtiest river in the world - Strel actually swam past dead bodies floating in its blackened waters).
The 52-year-old has even swum the Thames, proclaiming it, in his patchy English, to be "very ice and cold, but pretty clean - surprise for me". But Strel's greatest achievement to date is having conquered all 5,269km of the Amazon River in 2007 – a feat so great that it took him ?66 days from its start in southwestern Peru to its mouth in northeastern Brazil.
He has said he swims for "friendship, peace and clean waters around the world". But for the Amazon, his aims were a bit more specific: He wanted to raise awareness of the 700,000 sqkm of rainforest already lost to deforestation, most of it to cattle farming and illegal logging.
And if that meant donning a wetsuit and goggles to get people thinking, he was more than happy to do that.
We meet in a central London hotel after Strel's appearance on the Paul O'Grady show, where he is promoting Big River Man, the award-winning documentary of his Amazon swim, released on DVD last week.
In the three hours between returning to the hotel and our interview, Strel swims some 400 laps in the hotel pool and emerges, refreshed, in a black tracksuit.
"He cannot go a day without swimming," notes his business partner Kathy McGowan, with whom he is now establishing an American charity to raise awareness about Amazonian deforestation.
"He lives in the water."
Nicknamed "Fish Man", Strel was born in 1954 in Mokronog, a town in central Slovenia that translates, literally, as "Wet Feet".
As a child, he would jump into the icy stream at the foot of his garden to avoid being beaten by his father. To this day, Strel's mother hates to see her son swim and collapses in tears whenever she witnesses it, either in person or on film.
Even Strel's family is divided in their support. Though his son Borut, 28, is not only a swimmer himself but also his right-hand man (navigator, planner, logistics manager, translator, you name it), his wife and daughter both keep a wide berth.
"I like this, I can do this," he says of swimming, having also been a professional gambler and flamenco guitar teacher.
"I grow up around the water, I understand it a little more than regular people maybe.
"But I would like that it could be clean. My question everywhere is, 'Can I drink from the tap?' The answer is usually 'No'."
Strel has flirted with danger in the past. But his Amazon expedition was the most dangerous to date.
"I was told everywhere, by everyone, 'Martin, don't do it, you will die'," he says, explaining his high blood pressure is a risk for stroke or heart attack.
But Strel is a man of perseverance. Waking at sunrises so spectacular "they make you believe in God", Strel would slather his body in petroleum jelly (to avoid the scent of piranhas), wear a pillowcase over his face with eyes and nose cut-outs to avoid sunburn, and urinate in his wetsuit to avoid the deadly candiru fish (which swims into the urethra and attaches itself into the penis).
He claims that he avoided being eaten by any animals by "becoming" one himself and was awarded "police protection" by dolphins, who swam with him nearly the whole length of the river.
That said, Strel still suffered dengue, bilharziasis and larvae infections – in his brain – during his two months on the river.
And he still counts the "crazy desperate" Amazonian women as some of the greatest dangers he met while swimming.
Strel endured it all by entering into a hypnotic, "fourth-dimensional" state, in which two bottles of red wine a day helped him bypass the fear of the unknown.
"Many times I touch something – below the water could be crocodilies, anaconda, piranha, bull shark, you don't know," he explains.
"You could destroy your mind if you think too much about it. So I don't think."
A month into his voyage, hallucinations became frequent. His body gave out to shoulder strain, foot infections and second-degree sunburn.
"It's 66 days, long time. Every day is the same and you have to go in the water if you feel sick, tired, bad," he says, shaking his head.
"I almost drowned the last stroke, I was so empty."
It took a full year to recover physically, but even two years on, "you still question why you are alive", he says.
"Amazon was my dream. Because in my head Amazon was not possible to swim. It was a big challenge for me, doing the impossible."
Strel owes much of his success to his 30-strong team, notably Borut (who feared his father wouldn't survive), and river navigator Matt Mohlke, a 35-year-old Wisconsin native who's an expedition man himself.
"Martin is a difficult person to work with, because he is so demanding of his expedition team," says Mohlke, who wrote a book with Strel of the trip, The Man Who Swam The Amazon. "But I understand that. If I give him one wrong direction, I could kill him."
Two years after his return from the Amazon, Strel is still raising awareness about deforestation, through his blog www.amazonswim.com and talking to school children internationally about the importance of the world's rainforests (with a shellacked piranha in tow, for show and tell).
Influential figures such as Kofi Annan and Al Gore have also met him to discuss environmental issues, while the governments of Norway, Japan, Brazil and Sweden have all signed on to his rainforest fund to end Amazonian deforestation.
Keep up with the latest business news from the region with the Emirates Business 24|7 daily newsletter. To subscribe to the newsletter, please click here.