It depends if your Alaska cruise is departing and returning to the same US port, regardless of your itinerary ports. If it does, you are ok with a birth certificate, if it does not, you must have a passport.
answered 5 months, 3 weeks ago
YES. You will clear customs upon a return to the United States. Almost every cruise stop in a foreign port at least once. If you stop in Canada, you will need a passport to return to the US.
For US citizens, passport is not required. Birth certificate and a photo id are sufficient.
However, it is always advisable to carry a passport. In case you miss the ship and get stranded in a foreign country, you will need a passport to fly back.
Number One Contributor
You do not need a passport to get into Alaska. But a passport is needed to do some of the excursions into Canada.