We've had a lot of discussion about passports on here lately. Along with that there are some places where, when cruising, your passport is not enough. Be aware that the following list is an updated list of locations where U.S. and Canadian citizens will be required to have a visa if they are on your itinerary.
Also for sailings to South America, Africa, Asia/Far East, the South Pacific and the Middle East, always ask the reservation agent if vaccinations are necessary. Currently yellow fever shots are required by the cruise line for sailings calling on Brazil, Kenya, Indonesia, and Senegal. For more info on this you can visit www.cdc.gov