Blowing bubbles if you really know what you're doing, and they do

(Video courtesy of my friend Kelley.)
Rico says he doesn't begin to understand the physics, yet the dolphins obviously do. But it's amazing what a few million years of evolution will get you, if you have little to do other than explore the limits of your environment (especially if you don't have any hands, thus can't invent or use any tools to screw it up)....