The biggest of the flying-boat style fire tankers, the
Martin Mars, can't take off with a full load of water. Too heavy. It must take off empty, then skim the surface to scoop up 7200 gallons of water before lurching into the sky and heading for the fire. As the water is dumped, the whole handling characteristic of the aircraft changes. Very cool.
Brute force is now provided by DC10 and 747 Water bombers. They'll water your peonies for ya.