I am a night time swimmer too--but I don't think I'd do it off the cliffs, the beach is more my speed for nocturnal swims. I love floating on my back star gazing. The locals freak though and try to get me out of the water--saying sea things look for food at night. I think it may be more of a Jamaica thing than a real threat, I have swum at night all over the globe with no incidence and in Negril dozens of times. I have never heard of any disaster stories, but like Tizzy says, maybe in this case ignorance is bliss.