Les Paris Plages - Beaches in Paris?

Last Saturday afternoon, we went to the beach in Paris.  As you can see below, the city sets up a "beach" along the Seine; with sand, chairs, umbrellas, misting stations, ice cream stands, and games.  People actually put on their bathing suits and go there to tan, while others walk along the path in front and enjoy the ambiance.  It was 95 degrees that afternoon.  

Paris was the first to do this sort of thing, but it's spreading.  Tokyo has an even bigger one now.