Welcome aboard, Stefanie! You must be so excited to count down these last few weeks before you set sail! You're in for such magic and fun!
Disney's Port Adventures are able to be canceled up to three days before your sail date. After that, they are final and non-refundable. However, I must tell you that I've been to Castaway Cay in January for the past two years and it's always been warm and comfortable! Now, I'm a chicken about cold water, and while I'll admit it takes me a bit of time to ease myself into the water (even in July!), once I'm in, it's really refreshing, no matter the month!
If you're still concerned, there's another option that would allow you to snorkel but still be able to make the call about getting in the water once you are on the beach. Did you know that Castaway Cay has its own Snorkel Lagoon? No need to make Port Adventure reservations ahead of time for this, as there are always plenty of snorkel gear rentals available on the island for guests who walk up. Now, it's not quite as beautiful of a coral reef as you'll experience if you take one of the formal Port Adventures further off the coast, but it is still quite a bit of fun and Disney has hidden some surprises under the sea in this area. If you're on the hunt for Hidden Mickey's you won't want to miss this!
In St. Maarten, I would absolutely recommend one particular adventure for some beachy fun with shopping mixed in. The
French Riviera Beach Rendezvous is a great trip to Orient Bay, the most famous and picturesque beach on the island. You'll enjoy four hours on the beach, then have the opportunity to be dropped off in downtown Philipsburg for shopping before returning to the ship.
You will need to make your own way back to the ship from downtown, which is just a quick cab ride away.
Have fun planning!