Open water swimming is an activity in which people swim in large, outdoor bodies of water such as oceans, bays, lakes and rivers. In the first edition of the modern Olympic Games in Athens in 1896, the swimming competition was held in open water. The success of triathlon led to an increase in interest and participation in open water swimming. The triathlon made its Olympic debut at the Sydney Games in 2000 and involves an open water swim of 1500 meters (1.5 kilometers). Open water races of 5, 10 and 25 kilometers are held in the annual General Fina World Championships.