For some islands in the Carribean, passports are necessary for Americans. More importantly though, passports are necessary for Americans to re-enter the US now, from any other country.
No where in the Caribbean is owned by the US ( besides the Us Virgin Islands and Puerto Rico) So therefore you need a passport to get to most places in the Caribbean.
Only if you start or end in a foreign port. Cruises are considered closed circuit journeys and as long as you begin and end in the United States you do not need a passport.
If it involves going to another country, yes. And if your cruise lands somewhere other than Canada, Mexico, the Caribbean, or Bermuda, you'll need a passport book, not just the passport card. Source: http://travel.state.gov/passport/ppt_card/ppt_card_3926.html
Yes, you do need your passport.
does my passport need to be in date to go to belfast
Do you need a passport to travel to Barcelona
Yes you do have to have a passport to go to Chile.
You need a passport to go anywhere.
Yes. You need a passport to enter every country, but in some countries they do not accept certain passports.
You need a passport to go anywhere out of the country!
Yes, you need a passport to go to the Bahamas.
Passports are not required if sailing to the Eastern Caribbean. However, I highly recommend them. A certified copy or original birth certificate and government photo ID would work as well.