For many travelers, cruise day is the highlight of the year—the moment you finally trade traffic for turquoise waters. 🌊✨ But imagine arriving at the pier, bags in hand, excitement in the air… only to be told you can’t board. It’s rare, but it happens. And nothing can sink the mood faster than being turned away before your vacation even begins. To help you sail smoothly, here are the top reasons passengers may be denied boarding—and what you can do to prevent it. 1. Documentation Drama Expired Passport – Most cruise lines require your passport to be valid at least 6 months beyond your return date.