Open water swimming at the 2025 World Aquatics Championships

The programme consisted of a 10 km race, 5 km race, and 3 km knockout sprint, all of which had separate male and female races. The only mixed-gender event was the 4 × 1500 m relay.^[1] All events were contested in the waters near Sentosa Island in Singapore.^[2]

Germany's Florian Wellbrock won four gold medals, meaning he won every gold available to him in the open water events (the 10 km, 5 km, 3 km knockout sprint, and the mixed 4 × 1500 m relay).^[3][4][5] It was the first time this had ever been achieved at the World Aquatics Championships.^[6][7] Australia's Moesha Johnson won the women's 10 km and 5 km and won bronze in the knockout sprint.^[8]

The water temperature reached over 30.8 °C (87.4 °F), which means it was within 0.2 degrees of the upper limit of 31 °C (88 °F) that athletes were allowed to compete under.^[9][10] The World Open Water Swimming Association wrote that the conditions were "among the most extreme ever faced at a world championships".^[11] Several swimmers needed medical treatment and three were hospitalized.^[11][12]

Both the 10 km races, the first two events of the programme, were delayed due to poor water quality. The women's 10 km was delayed from 08:00 SGT on 15 July to 10:15 on 16 July,^[13] and then it was rescheduled again to 16:00 on the same day.^[14] The men's 10 km was postponed from 07:30 to 13:00 on 16 July.^[14][15]

Seven events were held from 16 to 20 July 2025.^[1] After taking place previously at other international open water swimming events, it was the first time the 3 km knockout sprint events were part of the World Championships.^[16][17]

For the individual events, each World Aquatics member federation could enter up to two athletes per event. For the team event, each federation could enter one team consisting of two athletes of each gender.^[18]