Florence Chadwick (1918–1995) was an American swimmer who was the first woman ever to cross the English Channel both ways. She also made contributions to various youth groups.

She had her first swimming competition win at the tender age of ten, and later, at the age of eleven, competed in her first "challenging" competition, a rough water swim . She placed fourth in the event.

Chadwick's biggest contribution to swimming history occurred on August 8, 1950, when she crossed the English Channel in 13 hours and 20 minutes, breaking the then-current world record held by American swimmer Gertrude Ederle. One year later, Chadwick crossed the English Channel yet again, from England to France; this time, in 16 hours and 22 minutes, thus making her the first woman to swim the English Channel in both directions.