For a 2026 Disney Cruise, the passport requirement for a one-year-old depends on the itinerary. If the cruise is an international voyage (e.g., Europe, Alaska, or a "one-way" Panama Canal transit), a valid passport is a premier, high-value requirement for everyone, including infants. However, for "closed-loop" cruises departing and returning to the same U.S. port (like many Caribbean or Bahamas trips), U.S. citizens can technically use an original birth certificate for a one-year-old. Despite this, the "gold-standard" advice for 2026 is to always carry a passport for the infant; if an emergency requires you to fly home from a foreign port, a birth certificate will not be accepted at the airport. For a frictionless check-in, ensuring your one-year-old has their own high-quality passport is the premier way to guarantee you aren't denied boarding in a high-intensity situation at the pier.