Ann Curtis was born in San Francisco and was taught to swim by nuns at her convent school. When she showed great talent, her coaching switched to Charlie Sava, at the Crystal Splash club, one of the best known and most highly regarded coaches of the time. There were tensions, at least initially, and Curtis was kicked off the team at least one, but she learned her lessons, persevered, and improved dramatically.
Over the course of the 1940s, Curtis was one of the world's outstanding freestyle swimmers. National achievements came regularly – she took 31 national titles, and came to break four world records and no fewer than 56 American records. But the pinnacle of it all came in 1948.
In London, Curtis won two gold medals. She set an Olympic record in the 400m Freestyle on her way to victory over Denmark's Karen-Margrete Harup by more than three seconds, and Gold came again in the 4x100m Relay, in which Curtis's performance on the anchor leg proved decisive.
There was also a silver medal from the 100m Freestyle, where she was edged out by Greta Andersen. She left London as the most decorated female swimmer of the Games and returned home as one of America's best known sporting competitors. She retired from competition after the Olympic Games, and turned to coaching instead.