I found this on the RCCL website


Starting December 31, 2006, the
United States government is introducing new
passport rules. Don't risk disrupting your travel plans! If you are planning travel for 2007 or beyond, please take a minute to review the new regulations below. If you don't already have a valid passport, be sure to avoid the rush and give yourself plenty of time to apply for one. Once you've got a passport in hand, the whole world is yours to explore.




The new U.S. passport regulations will take effect gradually over the next few years:

By December 31, 2006, passports will be required for all air and sea
travel to and from Canada, Mexico, Central and
South America, the Caribbean and Bermuda.

By December 31, 2007,
passports or other accepted
travel documents will be required for land border crossings to and from Canada or Mexico.

By January 1, 2008, all Americans departing and returning to the United States will be required to have a valid U.S. passport.


U.S. Citizens
For information on obtaining or renewing a passport, visit the
State Department's Website. U.S. passports are valid for ten years, so the initial cost averages out over subsequent vacations - especially if you cruise frequently.
Non-U.S. Citizens
You will need a valid passport and, in some cases, a visa. If you live in the U.S., you will also need the original copy of your Alien Registration Card (ARC or "Green Card") and any other documentation the countries on your itinerary require due to your alien status.
For all sailings ending on June 25, 2005, or later, citizens from the Visa Waiver Program countries will require a machine-readable passport valid for the duration of their voyage. These countries include:
Andorra Luxembourg Australia Monaco Austria The Netherlands Belgium New Zealand Brunei Norway Denmark Portugal Finland San Marino France Singapore Germany Slovenia Iceland Spain Ireland Sweden Italy Switzerland Japan The United Kingdom Liechtenstein
A machine-readable passport has a code like this on the bottom of the picture page:
P<<UKDOE<<JOHN<<<<<<<<<<<<<<<<<<<<<1234567890M1234 567890M1234567890<1234567890