That looks like a very nice package, especially over the busy holiday week! Did they charge you a single supplement? The package price includes most things like transfers, hotel taxes and service charges, all meals and 2 dives per day.
It doesn't include the dive shop tips or the afternoon dives. You may have done this already - but if not, you can add on 5 afternoon dives for a pretty decent price. At least the price has been pretty good in the past - like $150 if I recall correctly? But be sure to add the extra dives on in advance, the price may be higher if you add them onsite at the resort.
If you enjoy imbibing some alcoholic beverages on vacation be aware that your package doesn't include a drinks package and prices at the bar at the resort are pretty steep - and there will be a 15% service charge added to anything you buy at the bar - even a coke. You can add on a drinks package in advance that gives you 3 (well) drinks per day. And/or you can buy a bottle of liquor at the duty-free shop in the airport before you leave the US to mix some of your own drinks. When you travel from the airport you will see small grocery and liquor stores on the way to the resort. You can borrow a bike from the hotel and pedal over to the stores to pick up some mixers if you wish - but be aware that the stores are closed on Sundays - and bring a water bottle and a hat because it will be a hot bike ride! There is an ice machine for guest use right near the bar.
What times does your flight arrive at GCM and what is the departure time for your connecting flight to Brac? I'm asking because your meal package begins with dinner on the arrival day - but you can get lunch at the beach bar if you arrive early. Or if you have enough time on Grand Cayman - take the free shuttle to the George Town Yacht Club for lunch before you leave GCM.
There are a lot of CBBR fans on Scuba Board so let us know if you have any questions!
