I got a good one, theres a cave under the small marketplace where your escort mission for taking the mask off ends( where the npc takes you to the suposed smith but its stone, right before the purple boss), anyway, did the escort mission and right before the boss i noticed a cave icon right below me, i dropped down, entered, cool new place (for me anyway), fought a croc and talked to the npc there, andddd bugged npc, it duplicated, one stayed where he was the copie went on following the script....ok then...i exit the cave and... WTF the entire world was now under water , the sky box was gone and was replaced by the under water texture in the sky, with submerged "fog", sounds, everything, except i wasnt swiming.
The entire map was now "dry", the normal water bodies where gone and one of two thinghs happened, either the world sunk below the map or the water bed replaced the sky box.
This is 100% repeatable, i tested with a save before entering the cave, every time i enter the cave and exit , the entire world gets flooded lol.
The cave is cursed ! XD
img1:cave
img2:dry sea floor with under water sky box and effects