I do give a damn! (To steal a line from Clark Gable.). Thus, I must tell you that diving on the side of GC where the cruise ships dock is far from being "advanced", whatever the definition! However, there is one dive that is not to be missed. This is especially true if you are an u/w photographer. That dive is Stingray City.
Last time I was on GC, trips to Stingray City were done in the early afternoon from several of the dive shops. Thus, you may be able to get in a dive and make it back to the Captain's Table in time for the evening repast.
The dive is far from being "advanced" since you have a max depth of ca. 15-20 ft. However, you will have a chance to see as many as 25 Southern Stingrays winging their graceful ways around you--even taking a few bites of fish right out of your hand. If you are into "M", you can might get a stingray hickey or three!
Oh, yes, even if you are not an u/w photographer, the depth is so shallow that you can use an u/w "throw-away" camera and get some decent photos. They won't put Cathy Church out of business, but they might wow a friend or two!
There are lots of dive shops that go to Stingray City, so I suggest you go on-line and see which ones have a schedule that can dovetail with yours.
Scorpionfish