Speak with Baron Revilgaz in Booty Bay.
Baron Revilgaz has had me keep an ear out for rumors of the strange and out-of-place in Booty Bay and Stranglethorn. I don't usually put much stock in ghost stories, but I heard some sailors in the tavern talking about a haunted island off the coast. Water elementals and a raving goblin ghost, they say.
If you're going to go talk to Revilgaz, could you relay that story to him?