Jumpin' Cats! Have you guys seen this:
How awesome is that!?!
These dolphins blow a bubble into a turbulently roiling eddy, which causes it to become a bubble-ring (similar to a Gandalf-style smoke ring, actually) and then, being dolphins, decide to play with it in the most ridiculously cute fashion possible. Hydrodynamically, these rings are a kind of toroidal vortex, which in this case is made up of a combination of air and water moving as a kind of propagating vortex. Here are some pictures of human-made bubbles, with a discussion of the physics involved in these things.
EDIT: Turns out a geo-blogger had already talked about this: check out Riparian Rap!