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 Fish-Man Island. It is covered in a fog so thick that it blocks out all sunlight.
According to Kokoro, many pirate and commercial ships mysteriously went missing every year and, sometimes, a ship will be found sailing without any people onboard. 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.
Although some of the disappearances that have happened in the Florian Triangle can be attributed to Moria's scheme, the truth is that 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. It was barely seen by 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.