Today, Martin Strel, became the first person to swim the entire Amazon River. Strel completed his journey in 66 days, and averaged about 52 miles a day. His journey began in Peruvian territory and ended in the city of Belem, just north of Rio de Janeiro, Bazil. Amazingly he had a pretty easy time with the piranhas, crocodiles, anacondas and candirú in the area, but was a bit less lucky in regards to dehydration and sun stoke.
Strel seems to be no foreigner to adventure, having already swum the lengths of the Danube, the Mississippi and the Yangtze rivers.
Image info here.