He's a merman! No, he's Michael Phelps!

His secret is out! Michael Phelps is a merman.

Dubbed as the "Greatest Olympian of All Time," having broken world records and won an outstanding 8 gold medals in the 2008 Beijing Olympics, US tanker Michael Phelps has been captured by the lens of renowned American portrait photographer Anna-Lou "Annie" Leibovitz as a merman. Phelps appeared with award-winning actress Julianne Moore as they live out their 'Fantasea' from the "Little Mermaid" for the “Disney Dream Portrait Series." The photo was published in the June 2008 issue of Vanity Fair magazine

From John Frost's report on the Disney Blog:

Fitted in his silvery fishtail, Phelps was lowered into a backlot tank in Los Angeles used for underwater movie scenes. Leibovitz was on the outside, snapping away, communicating her instructions to Phelps via members of her crew.

“One of the most complicated shots I have ever done,” said Leibovitz. “I didn’t know if it was going to work, what to expect. I have to tell you, he was beautiful. Michael put on that tail and … he just became like a modern dancer. He just took to it and enjoyed himself and swam through this tank. I was blown away.”

For the four time “World Swimmer of the Year” (as designated by Swimming World Magazine), donning flippers was worlds away from the swimming competitions he’s used to.

“It was kind of weird to be able to put on a tail and swim around in a tank,” Phelps admitted. “To work with Annie and try these crazy sorts of ideas is really an honor and something I won’t forget.”

A host of US swimming stars, past and present, joined Phelps in the water and final image: Janet Evans, Rowdy Gaines, Brendan Hansen and Cullen Jones.

The 23-year old Phelps has won the hearts around the world with his amazing discipline and hard work. Even US Olympic swimming legend, Mark Spitz (who won 7 gold medals in the 1972 Munich Olympics) praises Phelps to epic heights, "It goes to show you that not only is this guy the greatest swimmer of all time and the greatest Olympian of all time, he's maybe the greatest athlete of all time. He's the greatest racer who ever walked the planet."

With a total of 16 Olympic medals, this Maryland-born swimmer is no merman. He didn't come out of the sea to be an Olympic swimmer. He is Michael Fred Phelps.

Michael Phelps poses exclusively for the August 25, 2008 edition of Sports Illustrated magazine in this photograph taken by Simon Bruty in Beijing, China on August 17, 2008.