Whether you can cruise with a passport expiring in three months depends entirely on your specific itinerary and the cruise line's policies. Many international cruises, particularly those visiting Europe, Asia, or South America, strictly require that your passport be valid for at least six months beyond the date the cruise ends. If you are on a "closed-loop" cruise (one that starts and ends at the same U.S. port) to destinations like the Bahamas or the Caribbean, U.S. citizens can often travel with just a birth certificate and ID, or a passport valid for the duration of the trip. However, many cruise lines (like Royal Caribbean and Norwegian) have their own internal rules that mandate a 6-month validity regardless of government requirements to avoid issues with local immigration. If your passport has only three months left, the safest course of action is to renew it before you sail to avoid being denied boarding at the pier.