Off the brisk coast of Sinnoh, was where Koikeanós once was.
An ancient civilization said to have been so vastly advanced compared to current day, that it was the origin of strange Pokémon like Varoom and Castform. Inventions like magmarizers and discs had also been reverse engineered from artifacts, scattered across all of the lands and seas by those who had visited long, long ago. All sorts of divinity had gathered there, with groups of Manaphy and Phione at the heart of it all.
Its people were as prosperous as they were magnetic.

However, it sunk under the tides. Its creations and people scattered in the churning waves of the endless sea.
Perhaps it was struck down for its hubris, or maybe sabotaged by those envious. Condemned to a fate of falling into obscurity and becoming mere myth.

That was, until an expedition team recently found and managed to bring Koikeanós up to the surface once more.
From Hoenn sailors to Unovan nobles, news of the once lost legend spread. People flocked to gather on the risen remains, some looking for treasures while others saw the place as somewhere to start anew.
The research team's small base was turning into the makeshift settlement of Marble Port, built on the bones of people long gone.

Unaware of just how deep the Ebbing Labyrinth beneath them was.