Conversation so far:
where do us citizens need visas to travel
can us citizens go to the caribbean without a passport
U.S. administered territories and commonwealths do not require U.S. citizens to possess a passport for entry. In the Caribbean, Puerto Rico and the U.S. Virgin Islands fall into this category.
what are the us virgin islands
The U.S. Virgin Islands include St. Thomas, St. John and St. Croix.

Question: do caribbean cruise passengers need a passport
Self-contained rewrite: do caribbean cruise passengers who are us citizens need a passport