For U.S. citizens, the requirement for a passport on a Bahamas cruise depends on the route. If you are on a "Closed-Loop" cruise (starting and ending at the same U.S. port, like Miami or Port Canaveral), you can technically travel with a government-issued photo ID and an official birth certificate under the Western Hemisphere Travel Initiative (WHTI). However, in 2026, travel experts and cruise lines strongly recommend a passport book. This is because if an emergency occurs—such as a medical evacuation or a missed ship—and you need to fly home from the Bahamas, you cannot board an international flight back to the U.S. without a valid passport. Furthermore, some specific excursions or nearby island visits may require a passport for entry. Relying on just a birth certificate is a "legal minimum" that leaves you vulnerable to significant logistical headaches in the event of any travel disruption.