1 THE NEXT MICHAEL PHELPS? Two-time Olympic gold medalist Caeleb Dressel, 24, broke the International Swimming Hall of Famer’s 100-meter butterfly world record, which had stood for a decade.

2 AGE IS JUST A NUMBER! That’s what four-time Olympian Ryan Lochte, 36, says about gearing up to be the oldest U.S. male swimmer to compete at the games. (Dara Torres competed at 41 in 2008, landing her the title of oldest swimmer ever to win an Olympic medal.)

3 PUTTING IN THE MILES “It really is a four- or, in this case, five-year journey to get here,” says two-time Olympian and five-time gold medalist Katie Ledecky, 24, whose training schedule includes swimming 10 times a week for two hours and three weekly weightlifting sessions. Some athletes will swim up to 20,000 meters in a day— more than 12 miles.