It is one of the most “scientific” discussions of these Olympics. Paris 2024: the swimming pool hosted at There Defense Arena for swimming competitions it would be “slow”in the sense that the athletes would seem to have longer times than those that would be expected and that were recorded for example at the Tokyo 2021 Olympics or the 2023 World Championships in Fukuoka. It was also noted that so far no records have been broken in this pool. The issue was initially raised by the authoritative specialized site swimswam.comwho already on the first day of competition compared the times of Paris with those of Tokyo and Fukuoka. All attention is focused on the reduced pool depth: 2.15 metersabout 80 centimetres lower than that of Tokyo 2021 and also lower than the depth of 3 metres recommended by the Work Aquatics: in shallower water, in fact, the reflection of the waves on the bottom of the pool can slow down swimmers.
The athletes’ times do seem to indicate that the pool is “slow”, but It’s still too early to give a definitive judgement in this sense: the races are not yet concluded and times above the standards are not being recorded in all races and in all categories, as also highlighted by Swim Swam itself. Furthermore, it is not necessarily true that the “fault” lies entirely with the depthbecause the athletes’ performance also depends on many other factors. Finally, even if the “slowness” of the swimming pool were confirmed, this It doesn’t mean it’s defective or poorly built.. Let’s shed some light on a question that is undoubtedly complex and in some ways counterintuitive.

Is it true that a shallower pool is “slower”?
“These are strange times, maybe the pool is too low”: this was said by Nicholas Martinenghiwinner of the men’s 100-meter breaststroke on Sunday, July 28, who took home Italy’s first gold medal in the 2024 Olympics. Both he and his rivals recorded times that were not particularly impressive, and the Italian swimmer was quick to point to the depth of the pool as a possible cause.
In fact it is known that in a shallower pool swimmers are slower. This is for two main reasons:
- When the athlete moves in the water he produces waves that propagate in the water. These waves can then reflect on the bottom of the pool and return to the surface, where they can create turbulence that disturb the athlete himself. Moving in more turbulent water is in fact more difficult because there is more resistance to overcome.
- In a deeper pool the water has more space to “make way” to the athlete’s body.
Generally these effects begin to become negligible at depths of at least 2 meters, which is why the World Aquatics had established 2 meters as minimum depth for an Olympic-sized pool. However, it is possible that in very high-level competitions such as the Olympics, where even hundredths of a second can make a difference, a shallower depth could have a measurable effect on the times of athletes. It is virtually impossible to say for sure, however, given the number of other factors that can influence performance.

Why the Olympic swimming pool in There Défense Arena is shallow
The swimming pool at La Défense Arena is temporary: after the Olympic Games it will be re-installed in a public centre near Paris. It was built by Myrtlea brand of the Italian company Castiglione swimming pools in the multipurpose arena of the same name which hosts the French rugby team Racing 92. With a view to sustainabilityin fact, the organization of Paris 2024 preferred to use existing structures as much as possible to reduce those to be built from scratch to the bare minimum.
Being a temporary and non-stable pool, therefore, the shallower depth compared to other Olympic pools is probably due to a compromise between construction needs (related in particular to the structural limit of weight that can be supported by the floor of La Défense Arena) and the need to maximize the number of seats in the stands (which is now 17,000). Another reason why the pool can be shallower is that will not host artistic swimming competitionswhich instead requires by law a minimum depth of 3 meters.

What factors determine the speed of swimmers?
If the Paris swimming pool is found to be “slow,” it may not necessarily depend solely on the depth of the pool. fluid dynamics It’s one of the most complicated branches of physics ever, so it would be a bit reductive to think that something as complex as Olympic swimming competitions are determined by just one parameter.
In fact, given the same technique and physical conditions, there are many variables on which athletes’ performances depend, and not all of them have a purely physical origin. For example, the water drain design and that of the lane separation lines have a role in absorbing the waves produced by the athletes and therefore indirectly in the swimmers’ times. The costume designwhich has a tangible impact on performance. Even the temperature and chemical composition of water have their effects, not to mention the Athletes’ nutrition and rest conditionswhich in turn also depend in part on the organization of the Olympic village. It cannot be completely ruled out that there are also psychological factors in play in a shallower pool, where swimmers have a closer visual reference (the bottom) that can influence their perception of speed.