Whether you need a passport to cruise to Hawaii in 2026 depends entirely on your ship's itinerary. If you are on a "Closed-Loop" cruise that begins and ends at the same U.S. port (e.g., round-trip from Los Angeles, San Francisco, or Honolulu) and only visits U.S. ports, U.S. citizens can technically travel with just a government-issued photo ID and an original birth certificate. The most famous of these is the Pride of America by Norwegian Cruise Line, which sails exclusively within the Hawaiian Islands. However, most other Hawaii cruises (like those from Princess or Holland America) are "International" because they are required by the Passenger Vessel Services Act to stop at a foreign port (usually Ensenada, Mexico or Fanning Island). For these itineraries, a valid U.S. Passport Book is mandatory for all passengers. A 2026 "pro-tip" is that even on a "closed-loop" cruise, a passport is highly recommended; if you have a medical emergency and need to fly back to the mainland from a foreign stop or even from Hawaii itself, the boarding process is significantly faster and more secure with a passport in hand.