As of this moment a certified birth certificate, along with your driver's license are enough to get you on board. So, if you are sailing within the next couple of months you will be fine. BUT, there are rumors afoot that sometime in the very near future that passports will be required by cruise lines, no matter what your ports of call. If you have time before your cruise I would urge you to invest the time and money to get a passport. Besides, they make traveling SO much easier.