In 2026, the passport requirements for a cruise depend heavily on your nationality and the "loop" of your itinerary. For most international cruises—such as those in Europe, Asia, or South America—a valid passport is mandatory and must generally be valid for at least six months beyond the date the cruise ends. For U.S. citizens on a "Closed-Loop" cruise (one that starts and ends at the same U.S. port, visiting only the Caribbean, Mexico, or Canada), a passport is technically not required by federal law; a government-issued photo ID and an original birth certificate are sufficient. However, the U.S. State Department and all major cruise lines (like Royal Caribbean and Carnival) strongly recommend a passport for all sailings. This is because if an emergency occurs—such as a medical evacuation or missing the ship at a foreign port—you cannot fly back to the United States from a foreign country without a passport. Furthermore, some specific islands, like Martinique and Guadeloupe, require a passport regardless of the cruise loop. For non-U.S. citizens, you must ensure you have the correct "Multiple Entry" visas if your itinerary enters and leaves different jurisdictions. Always check the "Travel Docs" section of your cruise app at least 90 days before sailing.