Deepdive Helmet

Deepdive Helmet is cloth head armor that allows an Engineer to breathe underwater.

Source
Deepdive Helmet is crafted by Engineers with a skill level of 230.

Prior to Patch 4.0.1, the schematic was sold in limited quantity by in Azshara. As that NPC has been removed, the schematic for this item is currently unavailable, though the item was not removed from the game, and characters that had learned the recipe retain it.