One of my favorite things to watch is gannets diving after fish, they can change their whole body into these little daggers, it's incredible. There was a show on the BBC called Nature's Great Events and one of the things they covered was The Great Tide, a feeding frenzy of predators going after sardines off the coast of Africa. You can find some footage of it on YouTube. Here's an excerpt of schools of sardines being pursued by gannets, dolphins, sharks, and even a whale. The gannets move as well under water as they do in the air: [youtube]http://www.youtube.com/watch?v=dBd4sNHBnYc[/youtube]