You are required to have a valid passport (whereas a photo ID and birth certificate used to suffice) for all cruises that visit foreign ports. On cruises that begin and end in the same port in the U.S., a government-issued birth certificate and government-issued photo ID (such as a driver’s license) will suffice though cruise lines recommend a passport because if for some reason you need to leave the cruise early from non-U.S. soil you may be in for a big hassle.
If you are not a U.S. citizen but live in the United States, you will have to carry your alien registration card and passport.
U.S. citizens travelling to Canadian ports of embarkation will require a valid passport. They should also be aware that offences like drunk-driving are considered criminal offenses in Canada, and those with a DUI or almost any alcohol-related offence on their record no matter how old could be turned away at the border.
Before you leave for the airport, attach to each of your bags one of the luggage tags sent by the cruise line, or one of the do-it-yourself ones the cruise line sent for you to print off at home. Make sure that you correctly fill in the tags with your departure date, port, cabin number, and so forth. You can find all this info in your cruise documents. Put a luggage tag on your carry-on as well, but keep your carry-on with you; luggage can take several hours to reach your cabin.