For the past week at the 2016 Rio Olympics, the best swimmers in the world have been racing to make history, and to grab a medal for themselves and their country along the way. While the athletes are undoubtedly incredible, they may have to share some of that credit with the pool itself, according to Sports Illustrated.

Experts and athletes agree that the Rio pool is a "fast pool," which is a reference to how it was designed and how those design elements benefit the swimmers. "A fast pool typically has at least three meters of depth to it," University of California’s women’s swimming team coach Teri McKeever told Sports Illustrated. "The deeper the pool is the better, because the splash or the turbulence and everything takes longer to get down to the bottom, and then it doesn’t ricochet back up into the swimmers." During the London 2012 Olympics, NBC ran a video segment about the fast pool at the London Aquatics Center as a part of its Science of the Summer Olympics: Engineering In Sports series, calling it "one of the most technologically advanced pools ever built." Four years prior, announcer and swimming legend Rowdy Gaines called the pool in Beijing "the fastest pool in the world." The pool in Rio is expected to produce just as many records as the one in London, and it's all by design.

Depth isn't the only thing that matters. Sports Illustrated reports that things like buffer lanes, lane lines, and gutters all help to break up waves and reduce ripples and turbulence, the reduction of which provides clearer sailing for the swimmers. Changes to swimsuits and the atmosphere of the venue are also said to play a role, and the athletes themselves still have to be at the top of their game to beat out the competition. "Yes, you want a good facility," coach McKeever told SI, "but also I think it’s the competition, it’s the emotion and everything else that helps with those world records."

[h/t Sports Illustrated via TIME]

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