Adam Malcolm, a University of Virginia grad student, won the Life Jacket Design Compeition with this innovative life jacket belt:
Malcom’s winning entry was essentially ... a slender belt worn around the waist. The unit would stay out of the way and not retain body heat. When activated either manually with a ripcord or automatically via a CO2 gas cylinder, slender, symmetrically-arranged air bladders stored inside the belt inflate rising up to surround the wearer on all sides. No secondary action, such as sliding flotation over the head, is necessary. You simply float much like you would in an inner tube.
Link - Thanks Jason!