How does an open water race start?

• Where from: "a fixed platform or in water depth sufficient for them to commence swimming on the start signal". At the main events it is a fixed platform.
• Positions: on a platform, each competitor has a position "as determined by random draw".
• Caps: every competitor starts wearing an approved swim cap.
• The countdown: the clerk of the course announces the time left at intervals, and every minute for the last five minutes.
• The flag: the chief referee holds a flag upright and gives short blasts on a whistle when the start is near, then points the flag at the starter.
• Take your marks: competitors "take up a starting position immediately in line with the start line where a platform is not used, or with at least one foot at the front of the platform".
• The signal: "both audible and visual", given when the starter considers everyone ready.
• An unfair start: a competitor who gains an unfair advantage at the start is given a yellow or red flag.
• Men and women: started separately when numbers require it. Even if they start together, the two races are separate events.
• The boats: escort and safety craft are placed so as not to interfere with any competitor at the start.

The command is take your marks, as in the pool.

Sixty swimmers leaving one line cannot be given lanes, so the draw gives each a fixed place and nobody can crowd the best spot. A signal that can be seen as well as heard reaches swimmers along a platform far longer than a pool is wide.