One wave, a deep-sea monster cresting about five or six feet above the water's surface, caught me by surprise and pulled me under. I was sucked into the undertow. Every time I tried to surface for air, the wave sucked me back under it. I tried to fight my way to the top as my lungs screamed for air. I tried everything I had learned in all my years of swimming, but nothing worked. I couldn't get to the surface.