Place the two divers (loop diver & hook diver) in a full plastic bottle of water (follow directions included with diver). Squeeze and hold the sides of the bottle and watch as the hook diver dives down. Try to hook the loop diver. Release the bottle and watch the hook diver float back to the top. This experiment is based on water pressure and will bring hours of enjoyment to you and your children. One and two liter plastic pop bottles work the best with the catch and hook diver. Bottle and water not included.