In the bays of Beaulieu-sur-Mer and of Ajaccio the charts have markings for "zone for alighting of hydroplanes".  No-one seems to much care about them, and  boats of all sorts cross these rather centrally located zones and even (illegally) anchor in them.

It is only when one hears the propeller noise —when these fire-fighting airplanes execute a warning flyby— that one realizes the French are not kidding.  In other countries, one might think a coast guard or police boat might come by and clear the field in advance.  Not in France.  Here, these fearless pilots just plunge in.

Bay of Ajaccio, 10 and 11 August, 2016.  Click for more photos.  In the last photo, two pick up water at the same time, side-by-side, one a bit ahead of the other.