Diving Helmet

Diving helmet is a special helmet for under water activities.

Drowning
Dwarfs lose health while submerged. When a submerged dwarf has less than 1/3 of health (1), the player will be notified:

From this warning the player has 1 in-game minute (in normal speed) to take the dwarf out of the water before he dies. This time maybe shortened if the dwarf receives damage from other sources other than the drowning.

Use
To counter this limitation dwarfs will automatically equip a diving helmet from the stockpile without ever going there, and despite already wearing another helmet or not.

Only one dwarf can use a diving helmet at the same time. For simultaneous uses, more helmets should be available at the stock, one for each diving dwarf.