Oh, hey Richard! I'm glad to hear from you again. You are getting closer and closer to your sail date, and you and your family must be so excited.
For December in the Bahamas, you can expect for temperatures to be in the high 70s F with water temperatures in the low-to-mid 70s. I personally would be a little chilly in water below 80 degrees, but if the weather is warm, the cooler water temps will feel great.
The
Extreme Getaway Package at Castaway Cay is a wonderful way to see and do it all on the island at a packaged rate, and the Port Adventure is quite popular among guests. Yet, you must book online prior to sailing or once onboard at the Port Adventures desk. You can't receive the discounted rate once you arrive at Castaway Cay. Since it is in winter, there probably will be availability once you're onboard and have a better idea of the weather conditions. Yet, you'll run into the
possibility of not being able to book the package for your entire party if there's not enough availability. So, if you have your heart set on it, I'd book the excursion before you sail.
I hope this helps put another piece of the puzzle into place for you, and you know that I'm here to help. Let me know if you think of more questions. Have a wonderful day and a magical vacation.
Bon voyage!
Andi