Explained: Paris Olympics’ swimming pool is being called slow… how can a pool be slow or fast?

Paris Olympics 2024: We’ve heard about badminton courts being slow or fast. But how can a pool be slow? The answer is a deep one. Literally.

Pan Zhanle, of China, celebrates in the pool after winning the men's 100-meter freestyle final at the Paris Olympics. (AP Photo)

On the fifth day of the Paris Olympics, finally Pan Zhanle made a splash at the swimming pool at the La Défense Arena: by smashing the 100m freestyle world record with a time of 46.40.

But when the Chinese swimmer broke the world record, it also emphasised something different: that in five days of the Paris Olympics, there has been just one world record that has been broken despite some of the biggest names in the sport like Katie Ledecky, Ariarne Titmus, Caeleb Dressel, Kristof Milak, Summer McIntosh, Kyle Chalmers, David Popovici competing.

This paucity of world records times has naturally been accompanied by conversations about how the pool for the swimming events is “very slow”.

Ledecky, one of the faces of USA Swimming, was also asked about the pool being too slow. “I’m not really thinking about it. We’re all fast swimmers. We make the pool as fast as we want it to be. I’ve heard the rumblings, but at the end of the day we’re here to race,” Ledecky said.

We’ve heard about badminton courts being slow or fast. But how can a pool be slow?

The answer is a deep one. Literally.

Experts have pointed out that the La Défense Arena pool’s depth of 2.15 meters is causing slower times. How? As long-time swim analyst Byron McDonald explained to Canada’s CBC News recently, most pools around the world that host world championships or the Olympics have had a depth of 3 metres since the 2005 World Championship.

Even though the two temporary Olympic pools inside the La Défense Arena were constructed by Italian company Piscine Castiglione which built pools for the past Olympics in Atlanta, Beijing, London, Rio and Tokyo, the depth for the Paris 2024 pool is much shallower, at 2.1 metres.

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Thanks to lesser depth, the water is more turbulent when you swim at the La Défense Arena. More turbulence means more resistance and friction. The deeper the pool, the calmer the water.

McDonald also pointed out that there was plenty of recording equipment at the bottom of the pools leading to more turbulence.