Want to explore the British Virgin Islands, even though you don’t have a passport? According to the U.S. Passport Service Guide, Americans can explore foreign territory by way of a closed-loop cruise as long as they have a government issued ID and a birth certificate. Be aware, though, that some cruises will require a passport and some destinations won’t allow travelers off the ship without a passport. It’s always best to check into the specifics of a trip to ensure you won’t need a passport.