located west of tarsis in the sirrion sea.
west of wayend.
find the southmost exit to the sea and go all west. things will start to vary from the 
regular sea that you encounter from other exits in that area.

there is a buff shark along the way, it does 100hp/round while you're standing, and 
fleeing from the room sometimes brings you back to it.
mystic isle and dark knights outpost is west of this shark.