New Atlantis

Separated into ten kingdoms that function as city-states, the islands of New Atlantis sit on a pillar in the middle of an impossibly deep expanse of water called "The Bottomless Ocean." Each of the ten kingdoms is ruled by an immortal monarch, the divine children of the first of the Gods of New Atlantis, Poseidon and Cleito. For most of their history since the establishing of New Atlantis, the kingdoms had existed mostly separated and unable to expand; a consequence of the calamity which ended the Great Atlantean Empire and caused monsters to take most of the land for their own. Then, five hundred years ago, an ancient god and ally of the New Olympians returned and his power reestablished an ancient pact which protected Atlantean settlements from assault by the powerful monsters who had been keeping the mortals at bay. In those five hundred years, the ten kingdoms have reestablished contact and trade with each other, and the monarchs have renewed their ancient vows of mutual assistance and cooperation. Despite the rapid advancements in technology and magic brought about by this newfound connectivity, the people of New Atlantis remain confined to their island chain; any vessels that sail off the shelf and into the truly deep ocean are taken by colossal denizens of the depths.