He worked out at the Meadowbrook Aquatic Center in Mount Washington for perhaps the final time on Saturday morning as he prepares for a fifth Olympics this summer.
Phelps was in town for the Countdown to Gold Gala, a fundraiser for the North Baltimore Aquatic Club, where the record-setting Olympian has trained for most of his career.
"My family has had a long history with this club," he said before the dinner. "For us, NBAC is always our home."
Though Phelps has spent this year training with his longtime coach, Bob Bowman, in Arizona, he's one of 18 swimmers currently qualified to represent NBAC at U.S. Olympic and Paralympic Trials this summer. The club also boasts three international swimmers who have qualified to swim in the 2016 Olympics in Rio de Janeiro.
Proceeds from Saturday's gala at the Boumi Temple in White Marsh will cover travel expenses for the club's Olympic and Paralympic hopefuls.
Phelps and fellow Arizona-based hopefuls Chase Kalisz, Allison Schmitt and Cierra Runge joked that they've dubbed their group "NBAC Southwest."
But Phelps said he has little doubt the Baltimore headquarters will continue pumping out Olympians after he's gone.