Follow Atticus Tylakios in his underwater journey to retrieve Mask of the Deep. Note: Do not go up to the surface for air (if you do you will fail the quest). He will lead you to air vents which you can right click on to regain your breath meter. At each one you will find an encounter. At the end of the journey, he leads you to a chest. Right click on the chest to loot Mask of the Deep. Turn in to Ruric in the Chancel of Labors, Iron Pine Peak.