If you're a U.S. citizen age 16 or older on a closed-loop cruise without your passport, you will need a government-issued photo ID like a driver's license that has your photo, name and date of birth. In addition to a driver's license, you must also present a document that proves your U.S. citizenship.

While "closed-loop" cruises (those that start and end at the same US port) technically allow US citizens to travel with just a birth certificate and a government-issued photo ID, in 2026, a passport is strongly recommended for several critical reasons. First, some Caribbean destinations—like Martinique and Guadeloupe—have made passports mandatory for all arrivals, regardless of the cruise loop. Second, if you have a medical emergency or a flight delay that forces you to fly home from a foreign port, you cannot board an international flight without a passport book. Third, the "REAL ID" requirements have made standard IDs more scrutinized at federal checkpoints. Most major cruise lines, including Royal Caribbean and Carnival, now explicitly advise that while a birth certificate is the "legal minimum" for certain routes, a passport ensures a much faster embarkation and disembarkation process and provides the only true "safety net" should your travel plans change unexpectedly while you are in international waters.