THE FLOODED WORLD FILLED WITH SAILORS, PIRATES, AND RELICS FROM A TIME LONG PAST BURIED UNDER SAND AND WATER!
Long ago there was a teeming civilization of humans. These people were studied and collected works of knowledge and understanding crystalized into artefacts and relics. They would keep these relics in the ground, creating many mountains with their hordes of knowledge. Overtime there was an awakening of territorialism which lead to the stealing and dealing of these items throughout the world creating hills and mountains full, like silos, with tomes, hoards, treasures, or sometimes skeletons, grudges, and fears.
Some of these mountains, so full of the hopes and worries of its creators, were so tall that they crested the sky and nearly reached whatever lies beyond. While the existance of divine beings in the world has never been proven in the scientific manner popular among the unnamed world's inhabitants, for one reason or another (though now popularly believed to be divine retribution for hubris) the land was flooded. Years of massive rainfall with no end brought destruction and choas to the previously meticulously ordered world. Most writing at that time was done on paper, and many of the artefacts were not resistant to water, and if they were it was not to the scale of water that came or the pressure that resulted from how deep under they were pushed.
After all was said and done, most life was wiped out and all that was left was the very tops of what were formally titanous geographical towers that now acted as the only semblances left of dry ground. Those scant few who lived high enough to avoid being drowned were hermits in their own right and hadn't interacted with those below since their emmigration several centuries before. After several thousand lifetimes of hoarding knowledge and creating a world for those who lived, almost everything was starting over.
There are plenty of job boards for anyone with a boat who can try to salvage metal and other materials from the junk machines that dirty the waterways and collect as deltas along the coasts and rivers of the many island countries. However, some nations have put together assesments to guarantee that their most highly sought after relics of the old age are handled with care and discretion. Meanwhile there are others who work as freelance sailors hauling resources from port to port or taking rich tourists on tours of the surrounding islands. And of course, wherever there is highly valuable items moving across the open sea, there are pirates.
While some islands have the size and/or resources to become states, most appartuses of power are made up of larger collections of islands. Sometimes close like an archepelagos, but others take great pride in the reach of their territory.