What must a swimmer do to stay on the course?
B · Beginner · The race · 3 of 4Swimmers must complete the whole course and respect every turn buoy and course boundary. Turn buoys are a different colour from the buoys that only guide. A turn judge is stationed at each change of direction and reports any swimmer who goes the wrong side. The water must be at least 1.40 m deep everywhere on the course.
How it works
- The whole course: competitors "are required to complete the whole course, respecting all designated turn buoys and course boundaries".
- Turn buoys: every turn must be plainly marked, and turn buoys "shall be of a different colour to guidance buoys".
- A long first leg: wherever possible there is a long distance from the start to the first turn, to ease the crush there.
- Turn judges: one at each change of direction, on a marked craft or platform placed so that it does not block the swimmers' view of the turn.
- What they do: make sure every competitor makes the turn as set out at the briefing, and report any infringement to the chief referee at once.
- Depth: "The minimum depth of water at any point on the course shall be 1.40 metre."
- Safe water: the venue needs a certificate of suitability from the local health and safety authorities.
- Tides and currents: the safety officer gives every competitor a chart showing tide changes and the effect of tide or current along the course.
- Fixed in place: platforms, turning apparatus and judges' craft must be secured against tide and wind.
Tricky cases
A swimmer goes inside a turn buoy by mistake. What should they do?
Go back and round it. A swimmer who has not respected a turn buoy has not completed the course.
Do swimmers have to pass close to the guide buoys?
No. Guidance buoys show the line. Only the turn buoys and the course boundaries must be respected.
Is the course the same length for everyone?
Yes, in the sense that everyone rounds the same buoys. A swimmer who wanders off the straight line swims further.
Why the rule exists
In open water the buoys are the course. Marking turns in their own colour tells a swimmer, who can see little from water level, which buoys must be rounded and which only show the way. A judge at every turn is the only check that each swimmer covered the full distance.
Where it differs
| Where | What changes | Source |
|---|---|---|
| World Aquatics rules | As above | OWS 5.1; OWS 9.1.3; OWS 9.1.6 |
| The finish | The last approach is a funnel of buoys that forms the boundary of the course | OWS 9.1.2 |
| An intermediate timing gate | If used, it is at least 6 m wide and on the swimming line | OWS 9.2.2 |
From the rule book
World Aquatics, Competition Regulations, Part Three: Open Water Swimming Rules (in force as from 1 January 2025), Articles 3.9, 3.12.4, 3.14, 5.1, 9.1.3, 9.1.5 and 9.1.6. Checked 14 October 2026. Official document: World Aquatics Competition Regulations (PDF).