Homemade Diving Apparatus

Step 3 Air hose

Many things would conceivably work here. I happened to use rubber aquarium hosing that I happened to have in a shed. This is about half an inch in diameter, and works fine. An old garden hose would probably be the most easily available thing. Just make sure you don't use drip irrigation hosing. It's riddled with little holes, and would leak A LOT. Other than that, just about any watertight hose would work. The way you attach it to the helmet and the pump will depend on the diameter of hosing you use, and the diameter of the helmet hose connection and bike pump nozzle. I'll leave that up to your ingenuity.