While sailing in the Mediterranean, Simon Sivertson wondered what it would be like to be dragged behind a boat. This activity is not new, but the device that Sivertson developed in response allows the user to stay underwater and have greater control over his/her movement. The Subwing has two hinged diving planes that adjust pitch and spin. This video shows a diver using one.
Company Website (warning: auto-sound) -via Dude Craft