Swimming pools are hot this year in France. Thanks to global warming, perhaps?
They don’t build them like we do here in California. They start with a concrete shell, and that’s where the similarities end. A plastic liner goes in the shell on top of a layer of felt (probably synthetic), waterproofing it and giving it a bit of give, for a softer feel. A series of clips holds the top of the liner in place – water pressure does the rest. To complete the pool, decking, tile or whatever goes over the clips so they’re not visible.
The liners come in various colors, and apparently even patterns. One company even has liners printed to look like mosaic, Definitely less labor than the real thing!