Welcome aboard, Lindsay! Oh, I simply love the
Disney Fantasy and the Western Caribbean itinerary. My family and I have sailed this itinerary quite a few times and have had such fun exploring those ports of call. You're in for such an adventure!
Since your cruise is a round trip sailing from a U.S. port, U.S. citizens are not required to have passports for that itinerary, however I do highly suggest obtaining one for each family member. Check out the
Passports and Travel Documents page of Disney Cruise Line's website for further details, but I'll give you a quick summary here. A passport or a passport card are both accepted for guests on this itinerary. Alternately, adult guests may bring a government issued I.D. (like driver's license) along with a state-issued birth certificate. Guests under age 16 traveling with their parents would just need a state-issued birth certificate if not traveling with a passport.
Now, having said all of that, and since you were already planning to get a passport, I'd highly suggest obtaining the full passport book. If you are going to pay for the passport card, go ahead and get the full passport book for the additional cost if possible. Having that full passport will allow you to plan other trips in the future too, and also provides you with the most protection should you find yourself in an emergency in a foreign port of call and needing to fly home. My kids, husband, and I keep our passports valid all the time now, ever since we started sailing with Disney, and have been so happy that we did.
Have fun planning this exciting cruise, Lindsay, and please stop back with any other questions about your cruise before you set sail. We're very happy to help!
Marcy