The Florian Triangle, (literally translated as Zone of Demonic Triangle) is a stretch of sea that one has to cross over when heading from Water 7 to Fishman Island. It is covered in a fog so thick that it blocks out all sunlight.
According to Kokoro, many pirate and commercial ships mysteriously go missing every year and, sometimes, a ship will be found sailing without any people aboard. It has also been said that there are many haunted ships with dead bodies sailing across the sea (though, it is revealed that all this is attributed to Brook).
Though, some of the disappearances that have happened in the Triangle can be attributed to Moriah's scheme. Ships have been disappearing mysteriously in it for a long time before he came on his ship, Thriller Bark, ten years before the series. This mystery is confirmed by an unknown ominous entity larger than Thriller Bark that was barely seen by Captain Lola through the fog. It is so large that it completely dwarfs Thriller Bark, the world's largest pirate ship, in sheer size, possibly making it the world's biggest creature to appear in the series thus far.