If you’ve tuned in to any Olympic diving events, you may have noticed that sprinklers spray water over the surface of the pool between dives. It seems like it could be to replenish liquid that sloshed over the sides after a dive—but world-class divers hardly make a splash. The Fédération Internationale De Natation (FINA), which oversees Olympic swimming events, mandates “surface agitation … to aid the divers in their visual perception of the surface of the water” [PDF]. In other words, the sprinklers create ripples across the water, which makes it easier for divers to see how far they are from the surface of the pool. And while it seems like Olympic divers are probably skilled enough to avoid this anyway, as you can see below, it has happened before.