I found a roped off section, maybe big enough to fit a small old-style ship inside, in the middle of nowhere.
Lots of oddities out there.
There's two or three (maybe more) roped off sections in the waters. These are somehow bugged locations.
One of them, near Tar Valon (the island next to Horseshoe Island), where there are the marble buildings and an entrance to the Lost Lands in one, you used to be able to drop down into. There was a marble room down there, part of an unfinished connection to the other marble buildings that was never finished upon the release of UO.
It makes me wonder what undiscovered things might still be under Sosaria's waters.