Polynesian Cultural Center
I've heard that the PCC is crazy awesome for Halloween! I wanted to go last year, but my wife was 8 months pregnant at the time and they have a funny way about not wanting to induce labor on their boat rides. Take what I have with a grain of salt because it's all second hand knowledge because I've never been, but my friends have told me that they take canoes and have people wearing snorkels jump out of the water at you. I heard that sometimes they have employees in the boats as part of the show and they'll pull those actors out of the boat and take them under water as part of the show. Pretty cool. I also heard the Oahu Ghost Tours are pretty good. Anyway, hope this helps!