What do you see that is unusual about the above photo?  Those are  square waves : This scene is off the Isle of Rhé, west coast France, where this natural spectacle occurs regularly. They form when two strong weather systems send opposing swells crashing into each other at different angles. They form quickly and vanish. But watch out! There is hidden danger. When square waves occur, they come with powerful currents and high waves, up to 10 feet. For swimmers and boaters, you are faced with unexpected forces of nature. Swimmers caught in these waves often feel as if they are swimming against two competing currents. Boats navigating these waters may be overwhelmed or swamped by the waves themselves. So what do you do? Simple, leave the water immediately, if you can. If caught, signal for help, and stay calm, floating on you back if needed, and try to swim parallel to the shore to escape the currents. Square waves have been linked to shipwrecks and drownings worldwide, not only i...