Although Phelps ended up beating the reef shark when it, uh, exhausted down the stretch, the hammerhead crushed him by over three seconds, despite Phelps having a special fin on his feet to put him closer to a level playing field.
Phelps wore a monofin on his feet as he swam a 100m butterfly race against the king of the water, clocking a time of 38.1 seconds - just two seconds slower than a great white. GREAT WHITE - 23-time Olympic gold medalist and swimmer Michael Phelps races a great white shark in the ocean (July 23).
Turns out, though, that Phelps, who can swim at a pretty astonishing rate of about 5 miles per hour (sharks cruise along at a leisurely pace of about 20 mph), used (the race already happened, but hasn't aired yet) a monofin.
SHARK SCHOOL WITH MICHAEL PHELPS - Phelps heads to the Bimini Shark Lab to take a shark crash course.
Fans will have to tune in to find out how Phelps fared against the ocean's most powerful predator when Phelps vs. Shark: Great Gold vs. The Olympic swimmer opened up about his experience racing a shark for Shark Week on Good Morning America, on the 20th of July.
10 p.m. - "Sharks and the City: New York" For decades, great white shark numbers were in decline in the waters around New York.More news: Starbucks customer turns would-be thief's own knife against him
Alien Sharks - Stranger Fins: (10 p.m. July 24) The search for some of the world's strangest sharks.
But there was still a chance of Phelps getting bitten, on account of him swimming in the shark-infested waters off the coast of South Africa - described by experts as "the White Shark's realm".
The race itself was basically just a timed race between Phelps and the CGI shark.
Other programs featuring the fish man most loves to hate will be shown throughout this week, and viewers may see them online.
The epic summer event takes place every year and focuses on everything shark. Long story short: If they were able to get Phelps to race a shark in an Olympic pool, he might have won, as long as he didn't get eaten.
"In a race, I think my fastest speed was about five or six miles per hour", Phelps says. "I had one, like I was saying, literally come right up to my nose, and it was insane".