A bubble ring
is an underwater ring vortex
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 toroidally as it travels through the water, much like a flexible bracelet might spin when it is rolled off a person's arm. Some scuba divers
can create bubble rings by exhaling air, and whales have also been seen to create bubble rings. Dolphins sometimes create bubble rings on purpose, seemingly for amusement.