If your cruise begins and ends in the same U.S. port, you do not need a passport. You do need a certified copy of your birth certificate...not a copy machine copy. I have heard that some states give birth certificates without a raised seal, but they are state certified copies. You need to be sure yours are certified copies that you receive from your state or county vital records office. If you want to call and ask to be sure yours are certified copies, see site below, scroll way down to the bottom and the phone number and email address, as wel as office address are there.