Your list looks good! Do you log your dives? If so then you should add your log book.
It's always a good idea to make copies of your passport and c-card and insurance cards and keep them separate from your wallet, because if you forget or lose them you will need that information available.
Remember that you will need to tip the crew at the end of the trip, but I think you will probably be able to put the tip on your credit card at the end of the week. I know that carrying a lot of cash isn't smart but I like to have some cash with me. Cash is almost always acceptable wherever you travel.
Make sure that your credit card doesn't charge foreign transaction fees; some cards add 1, 2, or 3% to purchases when traveling outside the US. We use the Capital One Rewards card and it doesn't charge fees for foreign transactions and we use the reward points for airfare on later trips.
I would add a pair of sweatpants (or other casual long pants) and a light long-sleeve, zip jacket to your list; the wind can get cold on the water at night and you may feel cold in the air conditioned salon or dormitory. They can also provide some protection from biting insects on land excursions.
If you have never done a lot of repetitive diving - like 4 dives a day for several days - you may find that that your fins/booties cause sores to develop on your feet. So a pair or two of socks might be worth having on hand. You can wear them while sleeping to keep your feet warm or put a pair into service to protect your feet while diving if needed. You will see a lot of "sock divers" out there - scuba socks work well but you may not need them if you don't have this problem.
Personally, I would add a couple of more t-shirts because wearing the same one or two shirts over and over gets stinky IMO but that's up to you. They used to sell Blackbeards t-shirts on the boat so that may be an option, but I don't know if they still do that. As others have said, you will definitely need some kind of safe footwear because they may offer shore excursions.
I would also include one or two paperpack books or download a couple of e-books in advance for light reading. They may help to pleasantly pass the time in airports, on planes, and up on the sundeck or in your bunk when you are relaxing between dives.
Is the Benadryl you've listed an ointment or a tablet? Be careful mixing Dramamine and other motion sickness meds with other oral medications. Blackbeards was my first LOB and we did a deep water crossing from Florida and I got very seasick. I was taking the motion sickness meds along with my daily anti-histamine allergy medications and the combination caused permanent changes to my eyes and vision.
I developed "floaters" that are like small shadows that randomly float across my vision - they are most annoying in the strong sunlight - and they will never go away. The ophthalmologist said that the combination of the motion sickness and allergy meds increased the pressure in my eyes and caused the formation of floaters. So you might actually want to read the tiny print that comes with the motion sickness meds for warnings about mixing drugs, or ask your doctor.
You mentioned sunscreen (good idea) but how about mosquito repellent? I always take some to the tropics. You won't need it for most of the trip while you are on the water, but it can come in very handy while on land. They sell it in small cans/bottles or in towelette packages, just be careful to properly dispose of the trash.
Have a great trip!
