It’s 11.00 on a bright spring morning in Slovenia, and Martin Strel is proffering a second glass of his home-brewed red wine. “Take it, drink, drink,” he exhorts. It’s hard to resist – the vintage is amiable but potent, much like Strel himself, a big bear of a man in his mid-fifties with biceps like tree trunks and a warrior’s resolve. These attributes have played their part in establishing Strel as possibly the greatest endurance swimmer the world has ever seen – with the scars to prove it.

“This,” he says brightly, indicating a nick on his arm, “was from a barge hitting me on the Mississippi. And this” – a big, angry-looking weal below his right shoulder-blade – “was from a piranha attack.”

Strel has swum the length of the world’s most daunting rivers, to highlight “the need for peace, friendship and clean water”. He started in a comparatively modest way – the English Channel in 1997, across the Mediterranean from Tunisia to Italy the same year – and built up to the Danube in 2000 (3,004km), the Mississippi in 2002 (3,797km) and the Yangtze in 2004 (4,003km). Strel swam the distances in one sustained burst, only taking lunch breaks (washed down with a bottle of the wine we’re drinking now) and overnight rests (though, he says, “I sometimes swam in my sleep.”) These feats culminated in April 2007, when he became the first person to swim the 5,268km of the Amazon, from the Peruvian Andes to the Atlantic shores of Brazil – 66 days dodging sharks, river pirates and machete- wielding tribes (but alas not piranhas).

“Everybody told me, don’t do this Martin, you will surely die,” he beams. “But I knew that, while the Amazon has a very strong power, it has a good spirit. And I hope I can help raise awareness of what we will all lose if the rainforest continues to vanish at the present rate.”

Strel’s Amazonian exploits were captured in a documentary, Big River Man, that debuted at the Sundance film festival this year and will surely spread Strel’s fame beyond the borders of Slovenia, where he is revered as an embodiment of the national virtues of pluck and individuality. “Slovenia is a young nation,” says Strel’s son and business manager Borut. “Martin has become a sort of focus for national pride and a symbol of hope.”

Slovenia is also a small country – the population is just over two million – which means that virtually everyone feels they have a stake in Strel’s success. “If I am out walking, it is impossible for me to get home,” he grins. “Everyone is saying, ‘Martin, please, come and share a glass with me, tell me all about the swimming.’ By the time I get home I am drunk.”

If Strel feels the need to “give something back” to Slovenia it’s because, he says, his country was instrumental in shaping his sensibility. We’re talking at the family compound, in the pristine countryside an hour or so out of Ljubljana; pure Alpine air blows through a patchwork of virgin-forested hillsides overlooking the azure lakes where Strel started practising his craft at the age of five. “I always felt water was my element,” he says. “It is maybe my first home. I understand it better than most.” His powers of endurance were honed along with a generous non-conformist streak – he was, he says with some pride, beaten regularly by his parents and teachers as a child, and deserted from his national service with the Yugoslav army no fewer than 37 times. His original ambition was to become a gymnast, but his coach believed he was a born swimmer.

Strel turned professional at 24 and became part of a crack group of marathon swimmers, but his lone-wolf sensibility led him to break away and embark on his remarkable string of solo swims. “You have to be a little bit crazy to do what I do, sure,” he says gruffly. “But I show by swimming these great waterways how connected we all are. Rivers join states and nations together and are ignorant of national boundaries.”

Strel’s mental preparation for a 6,000km swim is, if anything, more rigorous than the physical. “In the Amazon, for instance, I am in the water 10 to 12 hours a day,” he says. “So you do not want to empty your mind – you will have hallucinations. You do the opposite. I have conversations with myself all the time. I talk and laugh and in this way I hypnotise my body. It helps me ignore the pain.” The end of the Amazon adventure may have been the ultimate proof of the efficacy of Strel’s methods – he was hauled out of the water with his blood-pressure at heart-attack levels and whisked off to hospital, but, he insists, felt “right as rain” the next day. He further avers that he’s feeling at his physical peak, while tapping his growing paunch (he loses an average 30kg during each swim).

As he sits among his trophies, he’s planning his next move; a range of motivational spoken-word CDs and a possible crack at the Nile. “The Amazon was maybe 50-50 in terms of whether I would survive,” he says, knocking back his wine. “The Nile, with the pollution, the amoeba, the militias – this could be 30-70 against me, I think.” Strel grins broadly. Those are the kinds of odds he likes.

1950s: Grows up in the countryside outside Ljubljana, swimming in the Alpine lakes and catching trout with his bare hands.
1964: Aged 10, Strel challenges a group of Yugoslav soldiers to a race in his local pool. Beats them, and wins a crate of beer.
1978: Becomes a marathon swimmer, taking part in races from Capri to Naples, Suez Canal, and North American lakes.
1997: Solo swims, across the English Channel and the Med from Africa to Italy.
2000, 2002, 2004: Swims the Danube, Mississippi, and Yangtze respectively. Survives pollution in first, a lightning strike in second, and savage undertows in third.
2007: Swims the Amazon. Larvae burrow under his skin, and he has to wear a pillowcase over his head to stave off second-degree burns from the sun.
2009: Big River Man, a documentary about Strel’s Amazon swim, is released worldwide.

It’s 11.00 on a bright spring morning in Slovenia, and Martin Strel is proffering a second glass of his home-brewed red wine. “Take it, drink, drink,” he exhorts. It’s hard to resist – the vintage is amiable but potent, much like Strel himself, a big bear of a man in his mid-fifties with biceps like tree trunks and a warrior’s resolve. These attributes have played their part in establishing Strel as possibly the greatest endurance swimmer the world has ever seen – with the scars to prove it.

“This,” he says brightly, indicating a nick on his arm, “was from a barge hitting me on the Mississippi. And this” – a big, angry-looking weal below his right shoulder-blade – “was from a piranha attack.”

Strel has swum the length of the world’s most daunting rivers, to highlight “the need for peace, friendship and clean water”. He started in a comparatively modest way – the English Channel in 1997, across the Mediterranean from Tunisia to Italy the same year – and built up to the Danube in 2000 (3,004km), the Mississippi in 2002 (3,797km) and the Yangtze in 2004 (4,003km). Strel swam the distances in one sustained burst, only taking lunch breaks (washed down with a bottle of the wine we’re drinking now) and overnight rests (though, he says, “I sometimes swam in my sleep.”) These feats culminated in April 2007, when he became the first person to swim the 5,268km of the Amazon, from the Peruvian Andes to the Atlantic shores of Brazil – 66 days dodging sharks, river pirates and machete- wielding tribes (but alas not piranhas).

“Everybody told me, don’t do this Martin, you will surely die,” he beams. “But I knew that, while the Amazon has a very strong power, it has a good spirit. And I hope I can help raise awareness of what we will all lose if the rainforest continues to vanish at the present rate.”

Strel’s Amazonian exploits were captured in a documentary, Big River Man, that debuted at the Sundance film festival this year and will surely spread Strel’s fame beyond the borders of Slovenia, where he is revered as an embodiment of the national virtues of pluck and individuality. “Slovenia is a young nation,” says Strel’s son and business manager Borut. “Martin has become a sort of focus for national pride and a symbol of hope.”

Slovenia is also a small country – the population is just over two million – which means that virtually everyone feels they have a stake in Strel’s success. “If I am out walking, it is impossible for me to get home,” he grins. “Everyone is saying, ‘Martin, please, come and share a glass with me, tell me all about the swimming.’ By the time I get home I am drunk.”

If Strel feels the need to “give something back” to Slovenia it’s because, he says, his country was instrumental in shaping his sensibility. We’re talking at the family compound, in the pristine countryside an hour or so out of Ljubljana; pure Alpine air blows through a patchwork of virgin-forested hillsides overlooking the azure lakes where Strel started practising his craft at the age of five. “I always felt water was my element,” he says. “It is maybe my first home. I understand it better than most.” His powers of endurance were honed along with a generous non-conformist streak – he was, he says with some pride, beaten regularly by his parents and teachers as a child, and deserted from his national service with the Yugoslav army no fewer than 37 times. His original ambition was to become a gymnast, but his coach believed he was a born swimmer.

Strel turned professional at 24 and became part of a crack group of marathon swimmers, but his lone-wolf sensibility led him to break away and embark on his remarkable string of solo swims. “You have to be a little bit crazy to do what I do, sure,” he says gruffly. “But I show by swimming these great waterways how connected we all are. Rivers join states and nations together and are ignorant of national boundaries.”

Strel’s mental preparation for a 6,000km swim is, if anything, more rigorous than the physical. “In the Amazon, for instance, I am in the water 10 to 12 hours a day,” he says. “So you do not want to empty your mind – you will have hallucinations. You do the opposite. I have conversations with myself all the time. I talk and laugh and in this way I hypnotise my body. It helps me ignore the pain.” The end of the Amazon adventure may have been the ultimate proof of the efficacy of Strel’s methods – he was hauled out of the water with his blood-pressure at heart-attack levels and whisked off to hospital, but, he insists, felt “right as rain” the next day. He further avers that he’s feeling at his physical peak, while tapping his growing paunch (he loses an average 30kg during each swim).

As he sits among his trophies, he’s planning his next move; a range of motivational spoken-word CDs and a possible crack at the Nile. “The Amazon was maybe 50-50 in terms of whether I would survive,” he says, knocking back his wine. “The Nile, with the pollution, the amoeba, the militias – this could be 30-70 against me, I think.” Strel grins broadly. Those are the kinds of odds he likes.

1950s: Grows up in the countryside outside Ljubljana, swimming in the Alpine lakes and catching trout with his bare hands.
1964: Aged 10, Strel challenges a group of Yugoslav soldiers to a race in his local pool. Beats them, and wins a crate of beer.
1978: Becomes a marathon swimmer, taking part in races from Capri to Naples, Suez Canal, and North American lakes.
1997: Solo swims, across the English Channel and the Med from Africa to Italy.
2000, 2002, 2004: Swims the Danube, Mississippi, and Yangtze respectively. Survives pollution in first, a lightning strike in second, and savage undertows in third.
2007: Swims the Amazon. Larvae burrow under his skin, and he has to wear a pillowcase over his head to stave off second-degree burns from the sun.
2009: Big River Man, a documentary about Strel’s Amazon swim, is released worldwide.