What is the 3 km knockout sprint?
I · Intermediate · The competition · 6 of 6The knockout sprint is three races in one event. Everyone swims 1500 m in round one. The top ten from each heat go on to swim 1000 m, and the top ten from that round swim a 500 m final. Men and women race separately. A yellow flag from an earlier round stays with the swimmer.
How it works
- Three rounds: "In Round One (1) each competitor will swim 1500m, competitors advancing to Round two (2) will swim 1000m, and competitors advancing to Round three (3) will swim 500m."
- Separate races: men and women swim separately.
- Entries: each federation may enter up to two men and two women.
- Round one to round two: the top ten finishers from each heat advance.
- Round two to the final: with one heat, its top ten advance. With two heats, the top ten from each.
- Heats: the number is fixed once entries are known and announced at the team leaders' meeting. Heats are drawn at random.
- Flags carry over: a first infringement in round one or two "would remain in place" in later rounds.
- A gap in a later round: if a swimmer is disqualified or withdraws from round two or three, the next finisher takes their place and those below move up.
- Video: the video review judge may enforce violations seen on the decision review system.
- Whether it is held: at the world championships it is included subject to agreement between World Aquatics and the organisers.
Tricky cases
Is the knockout sprint one 3 km swim?
No. It is three swims of 1500 m, 1000 m and 500 m, which add up to 3 km for a swimmer who reaches the final.
A swimmer gets a yellow flag in round one. Do they start round two with a clean record?
No. The first infringement remains in place.
Do the times from the three rounds add up to decide the winner?
No. Each round is decided on finishing places, and the 500 m final decides the medals.
Why the rule exists
A 10 km race takes two hours and can look uneventful from the shore until the last lap. The sprint packs heats, eliminations and a short final into one session. Carrying the yellow flag forward stops swimmers treating each round as a fresh chance to foul.
Where it differs
| Where | What changes | Source |
|---|---|---|
| World Aquatics rules | As above | OWS 1.3.2; OWS 3.17.4 |
| The 5 km and 10 km | One race with no rounds | OWS 1.3 |
| Olympic Games | Not on the programme set out in the 2025 regulations | OWS 1.2 |
From the rule book
World Aquatics, Competition Regulations, Part Three: Open Water Swimming Rules (in force as from 1 January 2025), Articles 1.2, 1.3, 1.3.2 and 3.17.4. Checked 14 October 2026. Official document: World Aquatics Competition Regulations (PDF).