Swimming is an ancient practice, as prehistoric man had to learn to swim in order to cross rivers and lakes. There are numerous references in Greek mythology to swimming, the most notable being that of Leander swimming the Hellespont (now the Dardenelle Straits) nightly to see his beloved Hero.

Swimming as a sport probably was not practiced widely until the early 19th century. The National Swimming Society of Great Britain was formed in 1837 and began to conduct competitions. Most early swimmers used the breaststroke or a form of it. In the 1870s, a British swimming instructor named J. Arthur Trudgeon traveled to South America, where he saw natives there using an alternate arm overhand stroke. He brought it back to England as the famous trudgeon stroke – a crawl variant with a scissors kick. In the late 1880s, an Englishman named Frederick Cavill traveled to the South Seas, where he saw the natives there performing a crawl with a flutter kick. Cavill settled inAustralia, where he taught the stroke which was to become the famous Australian crawl.

Swimming has been held at every Olympic Games. The early events were usually only conducted in freestyle (crawl) or breaststroke, as backstroke was added later. In the 1940s, breaststrokers discovered they could go much faster by bringing both arms overhead together. This was banned in the breaststroke shortly thereafter, but became the butterfly stroke, which is now the fourth stroke used in competitive swimming. Women’s swimming was first held at the1912 Olympics, and it has since been conducted at all the Olympics.

The current program has events for men and women in freestyle, backstroke, breaststroke, butterfly, individual medley, and relays. Both men and women compete in freestyle over 50, 100, 200, and 400 metres. Until 2020, the long-distance event for women had been 800 metres and 1,500 metres for men. At the2020 Tokyo Olympics, amen’s 800 metres and awomen’s 1,500 metres were added to the program.

Backstroke, breaststroke, and butterfly events are contested over both 100 and 200 metres. Individual medley is held at 200 and 400 metres. Men and women now compete in the same three relays: 4×100 metre freestyle relay, 4×100 metre medley relay, and 4×200 metre freestyle relay. Tokyo 2020 also brought the firstmixed 4×100 metre medley relay.

Since2008, at each Games two swimming events have also been held outside of the Olympic pool. Both men and women compete in 10 km open water races – seeMarathon Swimming.

TheUnited States has been, by far, the dominant nation in this sport at the Olympics, with 586 medals and 258 golds. At various times, Australia (67 golds, 206 medals),Japan (24 golds, 83 medals), and previously theGerman Democratic Republic women (GDR – East Germany) (32 golds, 74 medals [women only]), have made inroads into that dominance.

Almost all of the individual top medal winners are American:Michael Phelps, (23 golds / 28 medals)Mark Spitz, (9 / 11),Matt Biondi (8 / 11),Ryan Lochte (6 / 12),Jenny Thompson (8 / 12),Dara Torres (4 / 12), andNatalie Coughlin (3 / 12). The only non-American in the top 10 of the medal table is AustralianEmma McKeon, with 11 medals and 5 golds, including a women’s record for any sport with seven medals at Tokyo 2020 (equalling the mark ofMariya Gorokhovskaya in artistic gymnastics in 1952). With 23 golds and 28 medals, Phelps has won the most Olympic gold medals and medals by any athlete in any sport.

The governing body is theFédération Internationale de Natation (FINA), which was formed on 19 July 1908 in London, at the end of the Olympics, with eight founding members:Belgium,Denmark,Finland,France,Germany,Great Britain,Hungary, andSweden. FINA not only governs swimming, but alsodiving, high diving,marathon or open water swimming,artistic (formerly synchronized) swimming, andwater polo. As of 2022, FINA has 209 member associations.