This can only be done on the levels that take place at the surface of the water. Swim to the surface and hit to jump out of the water. Keep hitting to spin. You have to complete 4 rotations and land head first to get the trophy. If you land on your side you will belly flop! and be unable to move for a few moments. The best way to do this is grab a lighting bolt power up and speed to the top as fast as you can. You will get better height this way and it will allow you to do more rotations. Hold on the controller to level your fish.