泡沫环（bubble ring）是在水里的涡环（vortex ring），在环内充满了空气。当泡沫环在水里移动时，环内空气与附近的水都会呈角向转动（poloidal rotation），就好像当滚动一串柔软的手镯于手臂时，手镯会呈平移运动与角向转动一样。泡沫环角向转动越快，就会变得越稳定。图为日本岛根海洋馆的三只白鲸同时吹出泡沫环。

A bubble ring, or toroidal bubble, is an underwater vortex ring where an air bubble occupies the core of the vortex, forming a ring shape. The ring of air as well as the nearby water spins poloidally as it travels through the water, much like a flexible bracelet might spin when it is rolled on to a person's arm. The faster the bubble ring spins, the more stable it becomes. Bubble rings and smoke rings are both examples of vortex rings—the physics of which is still under active study in fluid dynamics. Devices have been invented which generate bubble vortex rings.