The Scuba Helmet is a piece of armor that can extend the player's time underwater, if they have Compressed Air Cells in their inventory. The Hazmat set will protect against most environmental dangers.
The Scuba Helmet's oxygen indicates your air left, and staying underwater will empty Compressed Air Cells.
When wearing the full Hazmat set, the player is protected from most environmental damage (radiation, fire, fall damage..), except potion effects - e.g. poison and hunger. The set is very weak, though, and will drain durability very quickly. When the armor is out of durability, it will not break, but it won't protect from damage anymore.
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