Source: Wikipedia
Janet Evans started competitive swimming as a child. By the age of 11 she was setting National Age Group records in the longer events. In 1987, she broke the world records in the 400-, 800- and 1,500-meter freestyle events. At the 1988 Summer Olympics in Seoul, she won three gold medals. In the games, she set a new world record in the 400-meter freestyle event; this record would hold for 18 years. Evans holds the current world records in the 800 meters (set in August of 1989) and 1,500 meters (set in March of 1988). Both records are the longest standing in the sport of swimming, each lasting through four Olympic Games.