Some countries are more relaxed about the 6 month passport validity rule. Canada and Mexico are the two most commonly traveled countries that do not enforce a six month validity for your passport. Again, please be sure to check with each countries entry and exit travel requirements before you go. As a general rule, you should have at least six months validity on your passport before you travel.
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As a general rule, passports should have at least six months of validity when traveling internationally. Most countries will not permit a traveler to enter their country unless the passport is set to expire at least six months after the final day of travel. That means if your passport has less than six months remaining until the expiration date, you should renew it right away! Adult passports (16 and older) for U.S. citizens are valid for ten years, while minor passports (15 and younger) for U.S. citizens are valid for 5 years. There are additional passport requirements though, and they differ from nation to nation. Be sure to check the entry and exit requirements for each country you plan to travel.
The answer is and no. If the cruise is what is considered a close end cruise you technically can go on a cruise without a passport, but you must have documents such as birth certificate, landed immigrant card. However, we do not recommend that you travel without a passport as you may have to return to the United States in an emergency and you cannot enter the country at an airport or border without a passport.