Look, the team at TravelPulse thinks
you should have a (well-used) passport, but if you don't-for whatever reason-you shouldn't give up the trip of your dreams. Most people do not realize that there are
plenty of cruises they can take without this piece of government-issued ID.
It's always better to have a passport for emergencies, and you should check with your cruise line, travel insurance provider and travel agent before you go, but there are a host of U.S. locations which have fantastic cruise ports as well as places outside the U.S. you can enter on a closed-loop cruise which departs and returns to the same port.
Just,
get your passport when you get back!