Abyssal Depths is the third and last zone in the undersea region known as Vashj'ir. The Depths are home to the ancient god L'ghorek, who is connected to something immense beneath the seafloor. The Twilight's Hammer cult saps life energy from this gigantic being to create "ascendants" for the coming war against Neptulon for control of the seas.
Also within the depths is the Abyssal Breach, the entrance into the Abyssal Maw itself, where more unknown horrors await.
The Abyssal Depths is the largest of the three underwater zones of Vashj'ir and found at the western most part. The Depths, as it's name implies, is farther below the surface.