A 52-year-old Slovenian swimmer became the first person to swim the entire 3,272-mile length of the Amazon River, his son said on Saturday.
Martin Strel ended a 65-day odyssey in which he fought against exhaustion and delirium while trying to avoid piranhas and the bloodsucking toothpick fish.
On Thursday evening he arrived in the Peruvian city of Atalaya, and his health had worsened. He was struggling with dizziness, vertigo, high blood pressure, diarrhoea, nausea and delirium, his website said.
He was also tormented by cramps, chronic insomnia, larvae infections, dehydration and abrasions caused by the constant rubbing of his wet suit against his skin, his website added.
Just days after he began swimming, Strel developed second-degree burns on his face and forehead, and his team feared the burns would develop into third-degree burns and become infected.
His team fashioned a mask out of a pillow case for protection, but Strel did not use it all the time because he complained it was too hot and made it difficult for him to breathe. His lips blistered, and scabs formed on his nose and cheeks.
But despite having difficulty standing and being ordered not to swim by his doctor, Strel insisted on night swimming to finish the course. Averaging about 50 miles a day since he started in the Amazon's Peruvian headwaters on February 1, Strel fulfilled his goal near the city of Belem, 1,515 miles north of Rio de Janeiro.
A Guinness World Records spokesperson said the organization would analyse data expected from Strel and his support team to determine whether he had established a new record.
If confirmed by Guinness World Records, it will be the fourth time the 52-year-old has broken a world swimming distance record.
In 2000, Strel swam the length of Europe's 1,866-mile Danube River in 58 days, and then broke that record two years later when he swam 2,360 miles down the United States' Mississippi.
And in 2004, he set a new world record after swimming 2,487 miles along China's Yangtze.
The swimmer, who is also known as "Fish Man," was accompanied by a team of 50 doctors and trainers in his trip from Peru to Brazil.
The Amazon is one of the world's longest rivers and is home to several species of crocodiles, insects and piranhas.