Keen-eyed observers of diving events at the 2021 Tokyo Olympics may have noticed a curious sight: water from a sprinkler sprayed on the surface of diving pools.
It may seem innocuous, but the spray is a safety feature not only for Olympic diving events, but also all international competition, as mandated by the Fédération Internationale de Natation (FINA). The organization, which oversees competition in six aquatics sports — swimming, diving, high diving, artistic swimming, water polo and open water swimming — requires it for all diving events.
Why? Because it's a surface agitator; it provides a visual cue for divers that helps them visualize where the pool is in relation to their dive. Essentially, it helps them judge when to enter their rotation as they dive into the water.
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Below is the applicable rule (5.3.11) of FINA's facilities guidelines:
"Mechanical surface agitation shall be installed under the diving facilities to aid the divers in their visual perception of the surface of the water. In pools equipped with an underwater bubble machine, the machine shall only be used for the purpose if it creates sufficient water agitation when working with a very low pressure; otherwise a horizontal water sprinkler system shall only be used.
Considering a horizontal sprinkler system is what's currently being used at the 2021 Tokyo Olympics, it appears as if a sub-surface bubble machine is also being used at the Games to help prevent diver injury.
Those aren't the only safety measures in place for athletes in diving events, either. FINA has rules in place for everything from light sources and glare, depth of diving pools, water temperature and color of floor tiles (if a pool serves a dual purpose for swimming and diving, which is not the case in Tokyo).