Endurance contest involving swimming, cycling, and running.
Triathlons originated in California in the 1970s and became an Olympic event in 2000. Olympic and world championship triathlons consist of a 1.5-km open water swim, a 40-km bicycle ride, and a 10-km run. The sport's most famous event, the Ironman triathlon, is held annually in Hawaii and consists of a 3.8-km (2.4-mi) swim, a 180-km (112-mi) bicycle ride, and a 42.2-km (26.2-mi) marathon run.