Air injection mask

To obtain it, get a diamond and two nautilus shells; it's a portable mask-shaped item (similar to gas masks in real life, but only the part that covers the mouth). You use it and Gain 40 breathing bubbles. It's not an equipment item like a helmet; it's only a usable item in your hand. To recharge, aim at the ground and click "use," but it has to be specifically underwater. Below coordinates 10 in any natural water source in the world, and an item designed to help miners enter flooded caves, move around, and mine underwater.