Yes, you can use a U.S. Passport Card for many cruises in 2026, but it comes with a major catch. The card is valid for "Closed-Loop" cruises (those that start and end at the same U.S. port) traveling to Canada, Mexico, and the Caribbean. It is a more affordable and portable alternative to the Passport Book. However, cruise lines strongly recommend a Passport Book for one critical reason: the card cannot be used for international air travel. If you have a medical emergency or a mechanical issue on the ship and need to fly home from a foreign port (like Nassau or Cozumel), the Passport Card will not be accepted at the airport. In 2026, the peace of mind provided by a full Passport Book is considered well worth the extra cost, ensuring that you are never stranded in a foreign country should your maritime itinerary change unexpectedly due to unforeseen circumstances.