Underwater, He's an Extreme Success

Tom Sietas, world champion breath-holder, holds three records in "free diving," in which competitors see how long they can stay underwater. (Courtesy Of Tom Sietas)

Overcoming that urge is the biggest challenge for free divers. Given that Sietas has exceeded the 10-minute mark for static apnea -- the technical term for holding your breath without moving -- Tetzlaff said it was hard to calculate the limits of what is humanly possible.

"I have to admit, I don't know, honestly," said Tetzlaff, who directs respiratory clinical research for Boehringer Ingelheim Pharmaceuticals. "Ten minutes is incredible. Maybe you could do another couple of minutes. I can guess that might be possible."

Sietas said he is careful not to push himself too far when free diving. He said he has never lost consciousness, although he came close a couple of times early in his career.

For now, Sietas is thinking about shifting his focus to deep diving and is contemplating training in the Red Sea or Mediterranean.

But he is also fiercely protective of the records he has set and served notice that he would aggressively respond to any challengers.

For example, he said, he was interested in the notion of a televised competition with David Blaine, the American illusionist and stuntman who held his breath for 17 minutes 4 seconds on "The Oprah Winfrey Show" in April. That marked a world record in the category that allows entrants to breathe pure oxygen beforehand. Sietas broke it five months later.

"David, of course, is a showman, but he's also a very great athlete," Sietas said. "It would make very dramatic scenery if we went head-to-head, but I am the better diver. I am very sure of myself."

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