For my high school graduation, my grandfather took me and my cousin (Gaven) on a cruise to Alaska in August 2014. We went on the Princess Cruise Line, and stopped at Ketchikan, Juneau, and Skagway. We took a train from Salem to San Francisco, where we boarded our cruise ship.
At the time that I went on the cruise, (I didn't think that I was going to be doing much traveling) I didn't have a passport. I had to make sure to bring my birth certificate in order to board the cruise. Since my vacation to Alaska, however, I have been to two other countries. I would recommend getting a passport because it makes the trip much easier.