What will make the Paris 2024 Olympic swimming pool fast or slow?

Olympic swimming rarely disappoints, and it starts on Saturday with the women’s 100m butterfly heats. As excitement builds, many are wondering if the pool will produce record-breaking performances to light up the Games.

First things first; in Paris there is a separate venue for the swimmers in Nanterre while the divers and artistic swimmers get to star in the £151m purpose-built aquatics centre in Saint-Denis. So much for the hype around a flexible pool. Instead, the swimming events will be held in the Paris La Défense Arena where two 50m temporary pools have been built in what is normally a 30,000-seat rugby stadium.

Swimming in a rugby stadium?

Many swimming competitions are held in arenas made for other sports, chiefly to increase the number of spectators, and the decision to do this for Paris 2024 has had a largely positive reaction with 15,000 plus seats at the venue. “I love the idea of more and more people watching swimming,” said the Australian star Bronte Campbell, who will be competing in her fourth Games. “The bigger the crowds, the better. Maybe they’ll make enough noise that we can finally hear them underwater.”

Australia’s Zac Stubblety-Cook, the reigning Olympic champion in the men’s 200m breaststroke, emphasised the impact of the size of the arena. “Going into this arena, even the pool deck space, is really, really incredible. Being able to walk around and having space is actually a small detail but something that everyone has noticed.”

Does the pool really make much difference?

In a sport where the difference between gold and silver could be as little as a hundredth of a second, the conditions of the pool can be decisive. The company that has built the pools at La Défense is the same one that has done so at the past six Olympic Games. Strict World Aquatics regulations govern technical aspects such as pool depth and lane rope width, for example. Beijing 2008, when 25 world records were broken, set the standard to beat for a fast pool.

So what makes a pool fast or slow?

You may have heard about the difference an athletics track can make on performance, with the new purple track at Paris said to be 2% faster than the one at Tokyo, and the makeup of a swimming pool can also impact speed, both psychologically and scientifically.

There are four main factors that can determine the pace of a pool. The depth of the water, which should be deep enough to reduce the impact of waves hitting the bottom of the pool as this causes turbulence, but shallow enough for the swimmers to see the floor and use the tiles as reference points for their speed. Historically, the Olympic standard of three metres is seen as the optimal depth. The temperature of the water should be within the requirements of World Aquatics, between 25C and 28C, so that swimmers can warm up properly but not overheat.

Next, the gutters need to be big enough to absorb the effect of waves hitting the sides of the pool. Gutters that are too small leave swimmers in the outer lanes at a disadvantage, as they would be more affected by turbulence. At the Olympics the outer two lanes are unused to create a more level playing field. Finally, non-slip starting platforms allow swimmers to make a powerful start.

So will Paris 2024’s pool be quick?

The pool is shallower than the 3m standard, at 2.30m and there have been some questions raised over the effect this will have. The starting platforms have fins that allow swimmers to really push off at the gun. And one of France’s faces of the Games, swimmer Léon Marchand, believes it will live up to expectations.

“The pool is superb,” he said. “I loved the feeling I had in the water, the depth which is the same along the entire length. So you feel like you’re swimming fast and that’s cool. It’s a beautiful pool.” If swimmers are feeling fast in the pool at La Défense, we could yet see some new world records.