Bubble rings are circular formations of air that are created underwater. They occur when a stream of air is released from a person's mouth or a device, causing the air to form a ring shape as it moves through the water. The surface tension of the water helps maintain the ring's structure, allowing it to travel in a forward motion. These rings can vary in size and can be influenced by factors such as water currents and the force of the air released. Bubble rings are often seen in marine environments and are sometimes used in demonstrations by divers or in scientific studies related to fluid dynamics.