In a previous life before all things digital entered my life I used to work on the water. Sometimes I would take some guys out from Falmouth and they would go diving. I would circle a buoy for what felt like hours waiting for one of these babies to pop to the surface. This often meant that I would be hauling in some Treasure from the bottom of the ocean. Anyway this simple air bag would be able to lift up to 1 ton to the surface. I used to love waiting for one of these.