U.S. citizens can go on several cruises without a passport by utilizing the "Closed-Loop" loophole. This applies to cruises that begin and end at the same U.S. port and travel within the Western Hemisphere. Common destinations include the Bahamas, Bermuda, Mexico, and the Caribbean (including the U.S. Virgin Islands and Puerto Rico). Additionally, cruises to Alaska departing from Seattle and Hawaii cruises departing from Honolulu or California are passport-free for Americans. For these trips, you can travel with just a certified birth certificate and a government-issued photo ID (like a driver's license). However, in 2026, travel experts still strongly recommend a passport; if a medical emergency or mechanical failure forces you to fly home from a foreign port like Nassau or Cozumel, you cannot board an international flight back to the U.S. without a valid passport. Furthermore, some specific islands like Martinique, Barbados, and St. Barts have their own local requirements that may mandate a passport even for cruise passengers.