The Freestyle stroke is the fastest.
The 800m Freestyle race is 16 lengths of the pool. To start the race swimmers dive from the starting blocks. The turn in the Freestyle events is usually a tumble turn, although the Swimming International Federation (FINA) rules state any turn is legal as long as some part of the swimmer’s body touches the end of the pool before the turn.
All races start with heats. Swimmers are seeded according to FINA rules, based on the final entry lists. These seedings are used to determine the heat each swimmer starts in – the top seeds are placed in different heats. Seedings are also used to determine the lane each athlete swim in – the higher the seeding, the closer to the centre lanes of the pool.
The top eight swimmers from the heats progress straight to the finals.
Find out more about the women's 800m Freestyle competitions at the Olympic Games on the International Olympic Committee website.