Born in the former communist Yugoslavia, Strel became a professional marathon swimmer in 1978. "As a young boy I was beaten a lot by my parents and schoolmasters. This no doubt contributed greatly to my ability to ignore pain and endure," he says on his Web site.
A South African adventurer named Mike Horn did it a few years ago, but he used flippers and a half canoe/float thing called a hydrospeed.
Saw the film of it on the A1 channel. Twice he lost flippers and had to trek for a week through the jungle to get replacements, before returning to where he left off, and was almost killed by tribesmen who thought he was a river devil.