Soon he'll return to Baltimore a 23-year-old man.
Life will be different. This much, he concedes.
Just how different, he isn't sure.
"I want it to be as close to [normal] as possible," Phelps said in an interview the day after he won his eighth gold medal, the most of anyone in a single Olympics. "But I have no idea. I'll be able to answer that question when I get back [to Baltimore] and see it firsthand. I have no idea what it's going to be like."
But others, including his coach, Bob Bowman, and some of Baltimore's most famous athletes, say that Phelps' life - especially in Baltimore - will be drastically different.
In the short term, there will be a parade, though no date has been nailed down. And there is every indication that he and Bowman will expand and improve the facilities of the North Baltimore Aquatic Club.
Phelps, though, is unlikely to begin training again until February at the earliest, and he won't swim a serious race until the 2009 FINA World Championships in Rome in late July.
"My mom has told me that I better make the team, because she wants to go to Rome," Phelps said. "I have the pressure from the mom, so I guess we have to get back into it and make that happen."
In the interim, there will be countless mornings when he does not climb out of bed until the clock strikes at least noon. There will be Ravens games, evenings on the town with childhood friends, beautiful women and all the spoils of fame. He'd even like to play in the World Series of Poker, if he can sharpen his game in time.
"I'm going to live my life the way I always have," Phelps said. "I'm going to do the things I've always done and hang out with the people I've always hung out with."
Will that be possible? In 2004, Phelps was a minor celebrity, the subject of numerous magazine profiles and two books, but he was never going to be swallowed up by his own fame. In Ann Arbor, Mich., he was just another athlete on a campus full of them, arguably less recognizable than the Michigan Wolverine football players bound for the NFL.
In 2008, though, he has become the rare athlete whose accomplishments lived up to, and even exceeded, the hype. Even in Baltimore - a city that prides itself on the fact that Johnny Unitas was, until his death, a regular at the Brooklyn Park basement bar and restaurant Club 4100 - Phelps might find it difficult to be a man of the people. Like it or not, times have changed.
Fells Point residents and businessmen aren't trying to make too much of Phelps moving into the neighborhood.
"He has been in here before, several times, with a big group of people," said Adrienne Williams, manager of the Dead End Saloon on Fell Street. "But I'd shy away from saying anything but 'Congratulations.' People come in here to chill out; you don't want to scare him away from the neighborhood."
Bowman said Phelps needs to realize that his life is going to change.
"I think it will be different, particularly for him, as far as recognition or public [adoration]," Bowman said. "And I think it's going to be different than he thinks it will be. It will be like whatever Cal [Ripken] goes through. But it will be good for swimming."
Former Orioles Hall of Famer Jim Palmer said he's routinely recognized in public but that most exchanges are pleasant.