(CNN) — The world's rivers can be dangerous places -- at least if you're swimming in them. Marathon swimmer and Guinness World Record holder Martin Strel has navigated pirates, piranhas and parasites in more than two decades tackling some of the most menacing waters known to mankind.
The 67-year-old Slovenian recalls a moment back in 2004 when he was taking on China's Yangtze River. Mid-swim local people told him: "Martin, go home as soon as possible, you're going to die." Strel pressed on despite their warnings, successfully completing the swim and securing his fourth world record, swimming 2,487 miles in 51 days.
Although considerably easier than swimming the Yangtze, Strel's next pursuit is to swim Dubai's Water Canal. He will cover 50 kilometers (31 miles) to mark the 50th anniversary of the founding of the United Arab Emirates. The 24-hour event will begin on Friday December 10 at Burj Al Arab and finish at the Etihad Museum, taking him through the heart of Dubai.
Strel has been breaking records for over 20 years. Aged 46, he swam 1,866 miles of the Danube River in 58 days, and in 2002 he completed 2,360 miles along the Mississippi. Five years later he swam the Amazon, covering 3,274 miles -- roughly the same distance as from New York to the southern tip of the United Kingdom. It earned him the Guinness World Record for the longest open water swim, an accolade he still holds to this day.
Martin Strel swimming in the Amazon River in Peru, 2007.
Martin Strel via AP
During this treacherous swim, Strel encountered piranhas, bull sharks, parasites and suffered from dengue fever and severe sunburn. In his last few weeks he was under threat from pirates and had to keep a security crew around him at all times. His most frightening moment, however, was when his son -- who was aged 26 and had joined him for part of the swim -- was temporarily paralyzed after being stung by a stingray.
"There is no hospital. There are no roads. It's only water and lots of trees, more than a hundred meters high," Strel recalls. "If you call a helicopter, where is it going to pick you up?" Thankfully his son made a full recovery, but it serves as a reminder of the high stakes that come with these achievements.
An unusual athlete
Strel might not seem like your usual athlete: he weighs 240 lbs (110 kg) and drinks almost a bottle of wine every day. "I'm not like Michael Phelps or Ryan Lochte, but I can swim," he says. "You have to start and then you have to finish. All that's important is the result."
He does, however, have a rigorous training regime, made possible by living in the Slovenian countryside for part of the year (he spends the rest of his time in the US). "I swim every day, usually twice a day," he says. "I do cross country skiing and then hiking and gymnastic exercises."
Strel has also trained his brain to get through his strenuous swims -- which sometimes see him take to the water for 12 hours straight. He talks to himself while he's swimming, almost as a form of self-hypnosis, and when he's in cold waters he thinks about being in the hot tub.
Strel developed his passion for swimming during his childhood in the small town of Mokronog, Slovenia. "Growing up there was no TV at that time, no radio, no newspapers. My home was forests, rivers and lakes," he says.
His career path is as colorful as his personality. Strel was a soldier in the Yugoslav army before becoming a professional gambler. At the age of 30 he taught flamenco guitar and it was only later in life that he settled on long-distance swimming. When Slovenia became independent of Yugoslavia in 1991, Strel celebrated the occasion by swimming the entire length or Krka river (around 65 miles) in one go.
'Water is my best friend'
So why does he do it? Strel has swum in over 150 countries around the world and has seen first-hand the environmental challenges facing our waters. "I understand our oceans, rivers and lakes and there is pollution everywhere," he says. When swimming the Danube, he passed through cyanide-contaminated waters and to his horror found that "everything under the water was totally dead." Strel hopes he can raise awareness and promote clean waters globally.
Martin Strel swimming in the Danube.
courtesy Martin Strel Archive
His next big project is the World Swim. Starting next year, it will last 500 days, see him visit 130 countries and will cover approximately 6,835 miles. The project aims to inspire individuals, organizations and businesses to act in the face of the climate emergency. Strel also hopes this feat will earn him a sixth Guinness World Record.
Beyond that, Strel wants to continue to break records and has his sights set on being the oldest person to win at the Open Water Swimming World Championships and European Championships: "I'm too young for that now" he remarks," maybe at 75 or 80, that's my target."
But if he keeps on going at the rate he is, Strel will be ready when the time comes.
"I'll never stop swimming," he says. "Water is my best friend, it's my life."