Great Stirrup Cay is leased (or owned) by the cruise line. The only way to do that on your own is if you all bring your own gear. And, being novices, probably not a good idea to go on your own anyway. BUT, it is the best place to snorkel. Only traffic is that particular cruise line's ships, so water is crystal clear (unless there is a storm in the area). Sign up for the ship's snorkeling there and pretend I am with you. Please.....I am so jealous. Be aure and take an underwater camera, even a disposable one, as the array of fish can be awesome.