Well, they're not actually smoke rings. But from a physics point of view, they're the underwater version. In this collection of clips, all sorts of "toroidal vortices" are brought together into one video. Dolphins chase them. Belugas and humpbacks make them. Mount Etna blows them. Here's a definition of toroidal vortices, from the video description:

"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."

You might just be inspired to blow a few smoke rings above or below the surface, to start this week off right.

Beluga toroidal vortex