For a formal wedding, of course, you will want to bring a tuxedo, but remember you are in the Caribbean, and you might want to look at tuxedos that are light in color and less restrictive.
Also, remember that your bride is the star of the show and you will want to perhaps co-ordinate accessories/colors with her. This is a good thing and can buy you extra weeks of happiness.
Whatever decision you make on attire whether formal or casual, create a look that says you are serious and respectful of the tradition of marriage.
You can read the 10 Tips for Wearing a Tuxedo Here.