The swimming competitions at the 2016 Summer Olympics in Rio de Janeiro took place from 6 to 13 August at the Olympic Aquatics Stadium. The women's open-water marathon was held on August 15, and the men's open water race on August 16 in Fort Copacabana.
Open water quality.
The location for open-water events was a source of concern for athletes since scientists have found microbes in the waters off of Fort Copacabana and drug-resistant super bacteria off the beaches of Rio de Janeiro in 2014 and 2016 studies due to the daily dumping of hospital waste and household raw sewage into the rivers and ocean. Ten percent of the Copacabana water test samples contained drug-resistant super bacteria. However, during the races the water quality was good.
Events.
Similar to the program's format in 2012, swimming features a total of 34 events (17 each for men and women), including two 10 km open-water marathons. The following events were contested (all pool events are long course, and distances are in metres unless stated):
Schedule.
Similar to previous Olympics since 2000, with the exception of 2008, the swimming program schedule occurred in two segments. For the pool events, prelims are held in the afternoon, followed by the semifinals and final in the evening and the night session (due to the substantial fees NBC has paid for rights to the Olympics, the IOC has allowed NBC to have influence on event scheduling to maximize U.S. television ratings when possible; NBC agreed to a $7.75 billion contract extension on May 7, 2014, to air the Olympics through the 2032 games and is also one of the major sources of revenue for the IOC). The dates in the table are for August.
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Qualification.
FINA By-Law BL 9.3.6.4 (swimming) and BL 9.3.7.5.3 (open water) laid out the qualification procedures for the "Swimming" competition at the Olympics. Each country is allowed to enter up to two swimmers per individual event (provided they qualify), and one entry per relay; and a country may not have more than 26 males and 26 females (52 total) on its team.
Swimming – individual events.
On January 15, 2015, FINA posted the qualifying times for individual events for the 2016 Summer Olympics. The time standards consisted of two types: an "Olympic "Qualifying" Time" (OQT) and an "Olympic "Selection" time" (OST). Each country was able to enter up to two swimmers per event, provided both swimmers met the (faster) "qualifying" time. A country was able to enter one swimmer per event that met the "invitation" standard. Any swimmer who met the "qualifying" time was entered in the event for the Games; a swimmer meeting the "invitation" standard was eligible for entry, and their entry was allotted/filled in by ranking.
If a country had had no swimmers who meet either qualifying standard, it may have entered one male and one female. A country that did not receive an allocation spot but had at least one swimmer who met a qualifying standard might have enter the swimmer with the highest ranking.
Swimming – relay events.
Each relay event features 16 teams, composed of:
Open-water swimming.
The men's and women's 10 km races at the 2016 Summer Olympics featured 25 swimmers:
Participation.
Participating nations.
Brazil, as the host country, receives guaranteed quota place in case it would not qualify any qualification places.
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Medal summary.
Men's events.
 ;templatestyles src="Citation/styles.css"/ ;a Swimmers who participated in the heats only and received medals.
Women's events.
 ;templatestyles src="Citation/styles.css"/ ;b Swimmers who participated in the heats only and received medals.
Olympic and world records broken.
Women.
Legend: r – First leg of relay
References.
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