I saw of group of 3 willowwisps traversing the outer water regions of the zone today.
I tried chasing them down to kill them, but they went REALLY far out into the waters.
Here is a picture using bind sight to show how far out they go relative to the zombie ship
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At one point, it seemed to share the pathing of The Sea King- but I'm not 100% sure on that.
Edit:
Added Video to show pathing and teleporting
http://www.youtube.com/watch?v=yY2B-OBHO-A