The Sea of Corpses is the 5th layer of the Abyss. It is a vast frozen wasteland on top of a massive sea. It also is the last layer where it is physically possible for Delvers to return to the surface without losing their humanity or dying.
The 5th layer is the world that only White Whistle or Black Whistle Delvers (sources contradict; see [footnote 1]) delve into, and according to Shiggy, one can count the number of people who successfully returned alive with the fingers of one's hands. It is the thinnest vertical layer of the Abyss, being only 1,000 meters deep, but it is also the widest one horizontally, probably around ten times wider than the town of Orth. It consists mostly of a large sea with some crystallized sections held up by a large layer of thick mud and bones, hence the name "The Sea of Corpses." The water is filled with monsters of the sea, and diving deep into the water is synonymous with suicide. Not only are there dangerous creatures, but swimming back up would make someone succumb to the curse quite easily. Since it is the last section of the Abyss where it is physically possible to survive a return trip, it is quite common for White Whistle Delvers to settle down here for some time.
At the deepest point above the water, a Forward Operating Base named Ido Front was established by the White Whistle Bondrewd. Ido Front was originally the ruins of a former ritual site where preperations were made and the ritual was held. Ido Front gets its electricity from the rotation of the unstoppable whirlpool it is built upon. A device akin to an elevator exists in its center, the Altar of the Absolute Boundary, that is used to transport people through the sea and into the 6th layer. However, it can only be activated by a White Whistle, or more specifically, by a Life Reverberating Stone. Since Life Reverberating Stones are specially designed to be exclusively used by their original owners, the elevator is only available to those who have a White Whistle of their own.
Here, the curse takes the form of extreme sensory deprivation, first draining one of their basic senses to the point of Riko not noticing falling down a flight of stairs. The curse then quickly escalates into losing one's very sense of self (medically, it is called proprioception). This kind of deprivation also makes unintentional self-harm extremely likely, like when Riko clenched her jaw so hard that she broke her own teeth, not realizing the harm done until she put her finger in her mouth and saw blood.
Points of Interest
- In chapter 7, pages 15–16, Shiggy, while talking about the different layers, says, "Anyway, we're finally on to the fourth layer! Only Black Whistles and above can go here. [emphasis in original]" and "The fifth layer! This is the domain of White Whistles alone[.]"
This is contradicted in the second volume's chart which says the depth limit of Moon Whistles is the fourth layer and that the limit of Black Whistles is the fifth.
The original Japanese releases were investigated and there is no translation error.
However, in chapter 23, page 7, Bondrewd states in a conversation with another Delver, "Why bring this up now? It's also for this very purpose that I proposed Black Whistles enter the fifth Layer[.]"
This suggests a change in the depth limit has occurred at one point and as such, it is possible that Shiggy isn't aware of it.
|Places||Abyss • Orth •Beolsk • Sereny • Jeseku • Grand Pier • Gate to the Netherworld • Belchero Orphanage • Wharf • Delver Guild HQ • Laffi's Shop • Caravan Fleet • Burial Tower • Seeker Camp • Nanachi's Hideout • Garden of the Flowers of Resilience • Ido Front • Miniature Garden Of Dawn • Altar of the Absolute Boundary • Ilblu • Poriyon's Workshop • Ilblu's Market of Value • Mepopohon's Inn • Narehate Restaurant • Doguupu • Belaf's House • Camp 5|
|Layers||1st Layer • 2nd Layer • 3rd Layer • 4th Layer • 5th Layer • 6th Layer • 7th Layer|