What island? I suggest that you read the many comments of what to do in where-ever it is and who is recommended on the site where my name should be - you need to go to the PORTS section specifically for where ever it is about half way down the page
Apart from the answer below - could you not contact them yourself and ask which beach they visit. They will also be able to tell you which islands in the caribbean they operate on. Then someone here may be able to answer your question more fully.
Sorry I should have said Barbados Claire.