Florence Chadwick was an American swimmer who in 1950 swam across the English Channel in a new World record time of 13hrs 20min. The following year she completed a second crossing, this time from England to France making her the first woman to complete the swim in both directions.
In 1952 she attempted to swim across the Catalina Channel in California. Her first attempt was unsuccessful. She had been swimming for 16 hours and thick fog had set in. She abandoned her attempt, only to find out later she was just one mile from the finish.
Florence returned to the channel two months later.
Here is a wonderful account of that swim written by her friend Beverley Jackson.