Duckdiving
To get a good duckdive you must practice alot. Start the dive a good ten feet before the whitewater, depending on how fast it is approaching. Place both hands near the nose or on the sides and press down. Then place your knee near the tail and press down. When you come up, hopefully you will be behind the wave. Generally the places where the whitewater is flying in the air are the best to duckdive under.