OMG. Dolphins make circular bubbles and play with them! This a beautiful video, except you may want to skip the hydrogen bomb mushroom cloud (3:00 – 3:46) --
From Evasius, the Youtube poster -- Extraordinary and beautiful examples of toroidal vortices produced by dolphins, beluga whales, humpback whales, volcanoes, hydrogen bombs, and man.
A toroidal vortex, also called a vortex ring, is a region of rotating fluid moving through the same or different fluid where the flow pattern takes on a toroidal (doughnut) shape. The movement of the fluid is about the poloidal or circular axis of the doughnut, in a twisting vortex motion. Examples of this phenomenon are a smoke ring or a microburst. Vortex rings were first mathematically analysed by the German physicist Hermann von Helmholtz, in his paper of 1867 On Integrals of the Hydrodynamical Equations which Express Vortex-motion. Smoke rings have probably been observed since antiquity since they can easily be blown from the mouth.
http://en.wikipedia.org/wiki/Vortex_ring
