It is a good idea to pack a light weight jacket or sweater and a pair of pants. We just got back from the Western Caribbean and I was glad that I had a jacket on our snorkel excursion in Belize. While it was warm in the water it was cold when we got back on the boat and drove to our next stop. I also wore the sweater a couple of times in the theater. Our last sea day was also on the chilly side - 70 - windy and cloudy - I was glad I had long pants that day. Of course, if you don't pack anything warm it will give you an excuse to buy a sweatshirt or jacket on the ship if you need one! I hope this helps!