The final capital, the Ruinade Promos, is an injunction in the New World located in the belly of the seas at a depth of ten thousand meters. It is the source of the Great Seakame's origin and the farthest in-set location within the New World before Raftel itself.
Little is precisely known of the Ruinade Promos' past, aside from that it has been around since just after the discovery of the devil fruits. It is rumored that the Ancient Weapon Poseidon dwells in slumber there, or some other cataclysmic force, but even the highest ranking Marines seem to have no idea the location even exists.
The first known adventurers into it's depths belonged to the Fishmen race, and Arktoma Eta in particular is the foremost among the small list of them. The ancestor to Fisher Tiger was also there and took over after Arktoma's fall.
Writ below is the sum knowledge contained within the eight survived DSS. The hieroglyphs cast onto the surface are distantly related to the language found upon the Ponyglyphs of the Ancient Kingdom, in conjunction with certain usages from the Fishmen language.
Much to the Gorousei's frustration they have been unable to translate any of the details without the explicit aide of certain members of the Fishmen descended from the original explorers, and convoys to their native land to establish further progress was cut off following the incident with the Whitebeard Pirates and spliting of the Shichibukai's numbers again.
Dead Sea Scroll Volume the I
"We have found an outcropping that may yet prove capable of accepting the more violent of our people, as far from the young land crawlers as from our own home. The Sħinûmi that nearly defeated us will easily hold back any who would flee."
Dead Sea Scroll Volume the II
Dead Sea Scroll Volume the III
"We have learned their proper name is Hurui Okikame, these Sħinûmi. They are as fierce as the krakens guarding many of the depths no land crawler can pass, and few even of our own kind have dared explore into. They have agreed to work in truce to hold back the dangers, and we in turn will see their offspring delivered to light."
Dead Sea Scroll Volume the IV
Dead Sea Scroll Volume the V
Dead Sea Scroll Volume the VI
Dead Sea Scroll Volume the VII
"The Sense of Absertainty wielded by the Hurui Okikame has put to slumber the restless savages at last. As our tenth season grows to a close tension is arising within their kind, and I begin to doubt our truce will hold out much longer. It is time to speak with the land crawling elder again and accept his proposal."
Dead Sea Scroll Volume the VIII
"Cataclysm. Oaomaru's theory has proven true and many of the Hurui Okikame have been ritualized with their own abilities, breaking the race as a whole into new breeds. The worst of them have already died and the rest are willing to take exile far from our land and this realm as well, allowing us free reign to-"
After literally decades worth of effort, the Gorousei were able to utilize one of their Shichibukai members to figure out what dwelled there and turn it to their aide. The key to Oaomaru's puzzle is half-turned and awaiting the full engagement in order to awaken the stasis-kept Fishmen prisoners, savages so fierce that whole islands were ruined before Arktoma Eta and the others were able to subdue them and trek far into the hidious seas of the New World to be rid of.
With help from a device created by Dr. Vegapunk the prisoners have been carefully altered on a subconscious level to obey any command issued by one of Oaomaru's descendants upon awakening.
Following the release of the prisoners by the Yontsukiryu, the Saint Elysia Pirates came up against them in battle and found out precisely why such creatures had been sealed far away, only loosely obeying the orders of Scing Alur and massacring any thing that crossed their paths.
After losing a few of their kind against Inta's crew the remaining prisoners broke away from the Yontsukiryu and set about exploring the New World as it had become in the eight hundred years since they last saw it.
Many would return for the Battle of Exxod and among them only one would survive.