The Capital of the Unreturned, also referred to as the Bell Tower Layer, is the 6th layer of the Abyss. It is the point of no return since it is physically impossible to survive the ascent from here, hence the name. When a White Whistle Delver descends down to the 6th layer, it is called "The Last Dive," as none of them sees the surface ever again.
In the Capital of the Unreturned, the ruins of a majestic city sleep undisturbed. A rumor in Orth exists about a Golden City sleeping at the bottom of the Abyss, which originated from this very city within the 6th layer. The city itself is described as golden, however the ruins are covered by a crystal of an unknown color and density. It is unclear whether the buildings were intentionally made out of this crystal or if they became fossilized over time. The ruins themselves spread out in every direction, and oftentimes buildings are diagonal, upside down, or sideways. Creatures of Irrational danger level become quite common, as are random, bright geo-thermal explosions that emit poisonous gas. Bird repellent used on the information vessels does not work on the aviary species in the 6th layer.
The Curse that manifests upon ascending within the 6th layer subjects the victim to an inconceivable pain and leads them to mutate into a messy pile of meat. Humans sometimes survive the effects of the curse, but their intelligence and consciousness vanishes, and they devolve into a mindless pile of flesh with only basic instincts. Under certain circumstances humans will turn into Narehate rather than the mindless alternative. It is also possible for those affected by the curse to simply die, which, all things considered, is perhaps the more merciful outcome.