The Aquarium, the world's largest, has four whale sharks in its 6.3 million gallon tank, which is part of its Ocean Voyager exhibit. Divers are able to swim with the sharks in conjunction with its "Journey With Gentle Giants" program, which allows participants to swim in the Ocean Voyager tank with the whale sharks.
The invitation came by Tweet.
@MichaelPhelps We heard you want to swim with sharks- Come swim w/ ours at the world's largest aquarium!
The Tweet was accompanied by a photo ad that said, "Phelps, come swim with our sharks!"
There has not yet been a response from Phelps or from the U.S. Swim Team.