See this bit on the Velodrome in London: https://www.cyclingweekly.com/news/making-tracks-building-th...
You can see in the timelapse video here[1] the pool being built above the surface. They built it to a depth of 2.15m, the minimum required is 2m, but the recommended depth is 3m.
I can only assume that making it deeper would have cost more, and perhaps reduced the sightlines from the stands as the pool would have been higher in the arena?
[1] https://www.thesun.co.uk/sport/29555045/paris-2024-olympics-...
Paris Aquatic Centre -- Aquatics (water polo preliminaries, diving, artistic swimming)
Why not have those events at a different temporary facility? Feels like they did not avoid building a white elephant...
>Last Thursday, President Emmanuel Macron inaugurated the Olympic Aquatic Centre, but behind the flashes and smiles of the opening ceremony was a complex story that saw the budget increase by more than €115 million and the number of events reduced.
> From swimming lessons to recreational use and high-level competitions, the Aquatics Centre will be multifunctional. From July 2025, the Aquatics Centre will become a vast multi-sports facility open to all, including two pools (50m and 25m), a fitness area, bouldering area, paddle tennis section and pitches for team sports. It will also have an adjustable floor to serve a variety of purposes (swimming lessons for babies and children, etc.). The Aquatics Centre will also be the state-of-the-art facility that the French swimming community has been looking forward to for decades. The French Swimming Federation will be able to host national and international competitions in its four indoor disciplines. The Centre will also provide a best-in-class federal training facility for leading French athletes and will notably be home to the country’s diving centre
>This capacity, which may be overlooked by many, is not for World Aquatics, which requires a minimum of 15,000 for top-level swimming events, so France will not be able to host a World Championships
la defense arena has a capacity of 40000.