Swimming at the 2020 Summer Olympics – Women's 800 metre freestyle

The women's 800 metre freestyle event at the 2020 Summer Olympics was held from 29 to 31 July 2021 at the Tokyo Aquatics Centre. It was the event's 14th consecutive appearance, having been held at every edition since 1968.

Katie Ledecky won the gold medal, becoming the first person to win the event three consecutive times. At age 24, Ledecky became the oldest winner in the event after already being the youngest at the age of 15 in 2012.

Summary
U.S. distance legend Katie Ledecky won her third consecutive Olympic title in this event, joining Australian Dawn Fraser (100 free, 1956-64) and Hungarian Krisztina Egerszegi (200 back, 1988-96) as the only female swimmers in Olympic history to three-peat an event. Dominating the race from the start, Ledecky fended off a large charge by Australia's Ariarne Titmus to win gold in 8:12.79 - the 17th-fastest swim of all-time and of her career. Titmus, having bettered Ledecky in their 200 and 400 freestyle duels earlier in the week, lowered her Commonwealth record by almost two seconds to claim silver in 8:13.83.

Meanwhile, Italy's Simona Quadarella edged out the U.S.' 15-year-old Katie Grimes to earn bronze in 8:18.37. Grimes, the second fastest qualifier into the final following her teammate Ledecky, was unable to replicate her heat time and settled for fourth place in 8:19.38. Outside the 8:20 club, China's Wang Jianjiahe (8:21.93) and Titmus's teammate Kiah Melverton (8:22.25), picked up the fifth and sixth spots respectively, finishing 31-hundredths of a second apart from each other. Germany's Sarah Köhler (8:24.56) and ROC's Anastasiia Kirpichnikova (8:26.30) rounded out the championship field.

Records
Prior to this competition, the existing world and Olympic records were as follows.

No new records were set during the competition.

Qualification
The Olympic Qualifying Time for the event was 8:33.36. Up to two swimmers per National Olympic Committee (NOC) could automatically qualify by swimming that time at an approved qualification event. The Olympic Selection Time was 8:48.76. Up to one swimmer per NOC meeting that time was eligible for selection, allocated by world ranking until the maximum quota for all swimming events was reached. NOCs without a female swimmer qualified in any event could also use their universality place.

Competition format
The competition consisted of two rounds: heats and a final. The swimmers with the best 8 times in the heats advanced to the final. Swim-offs were used as necessary to break ties for advancement to the next round.

Schedule
All times are Japan Standard Time (UTC+9)

Heats
The swimmers with the top 8 times, regardless of heat, advanced to the final.