I would check for surface ice first! Don't worry, you will be in Jamaica, nice and warm. The one thing you want to assess before swimming off of the cliffs is if the sea has a chop on it, do you have the swimming skills to deal with that. Swells or rough sea can make it tricky to get out of the water. On a calm day, a confident swimmer will enjoy the sublime experience of swimming off of the west end cliffs.