A swimmer who has tackled the Yangtze, Mississippi and Danube is starting a bid to become the first person to swim the entire length of the Amazon.
Martin Strel, known as the "fish man", plans to swim the nearly 5,400km (3,375 miles) from Peru to Brazil, despite the dangers lurking beneath.
The Amazon, the world's biggest river, is home to piranha fish and crocodiles.
Mr Strel, 52, who is from Slovenia, acknowledged there were risks but said that it was his dream.
There are many potential pitfalls: poisonous freshwater stingrays, bull sharks, piranhas, anacondas, rapids, whirlpools, and the possibility of tidal waves.
But Mr Strel is philosophical. Speaking to the BBC, he said "I'm concerned of course, but if I think of that stuff I would never jump into the water."
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And when asked about the toothpick fish that can enter the body by swimming up the penis, and can only be removed by surgery, the marathon swimmer's practicality is as evident as his courage.
"I never urinate straight into the water, I always urinate straight into my wetsuit."
He says he is confident that his long-distance swim will go according to plan because of meticulous planning and the support of his back up teams.
More than 45 people, including doctors and trainers, will accompany him through Peru and Brazil.
And should he be attacked or concerned for his safety, he will be able to rely on the armed members of his retinue.
He plans to finish his swim in 70 days, averaging about 85km a day.
If he is successful, he will be able to add this feat to his other records.
He already features in the Guinness Book of World Records for swimming the Danube, Yangtze and Mississippi rivers.