I have always told people that penguins can fly. They just happen to fly in a different medium than we are used to birds flying in. Now it turns out the sometimes they even fly in the air. Not like this, (check it out anyway), but in air under water. Now I suspect you are getting really confused. Let me explain. I found out about a recent study via the BBC Wonder Monkey blog that documents just how penguins fly in the air under water. The research hypothesizes that penguins reduce drag in the water by using air lubrication to promote fast ascent when Emperor Penguins jump out of the water. You may have seen films of penguins (or observed swimming penguins in the wild) and noticed long streamers of bubbles trailing the swimming birds when they accelerate. That observation in the BBC film Blue Planet by the authors of the study, and a discussion about the reason for the bubbles over a beer before a conference, lead to a more detailed study. They determined that the bubbles were not the result of cavitation nor did the the enhanced ascent speed of the penguins result from buoyancy, but was a result of a reduction in the frictional and form drag on the penguin from air bubbles released from under the feathers of the bird.
In my observations of swimming penguins, I always assumed the that bubbles were emerging from under the feathers and I noticed it was most evident when the birds were accelerating, but I had no idea that it enhanced the speed of the birds in the water.
Check out the blog post here.
Or read the actual PDF of the research paper in the Marine Ecology Progress Series here.