Below is from Canival's web site but should be the same for RC.
What is required for proof of citizenship?
U.S. Immigrations determines the correct documents guests must have in their possession in order to travel. Proper travel documentation is required throughout the cruise and is the responsibility of the guest. Anyone not having proper documentation will be denied boarding at the port of embarkation without the benefit of a refund.
U.S. security procedures require all airline and cruise line passengers 16 or older to present official photo I.D. upon check-in.
The following documentation is required in order to sail on ALL cruise departures, including Cruises-to-Nowhere.
U.S. Citizens
• Passport, valid or expired less than 10 years or,
• Original birth certificate and a photo I.D. or,
• Certified, state issued copy of a birth certificate and a photo I.D. or,
• U.S. Military I.D., valid or expired, and a photo I.D. or,
• Original naturalization papers and a photo I.D.
Canadian Citizens
• Valid passport or,
• Original birth certificate and a photo I.D. or,
• Certified, state issued copy of a birth certificate and a photo I.D. or,
• Original naturalization papers and a photo I.D.
U.S. Resident Aliens
• Valid Alien Resident card (green card) with photo I.D.
Aliens (Non-U.S. Citizens)
• Valid passport
• Valid, unexpired U.S. Multiple Re-Entry Visa
• Aliens eligible to apply for admission under the Visa Waiver Pilot Program must have a valid unexpired passport
Debarking in Mexico Over 24 Hours
To debark for more than 24 hours in Mexico, guests must have obtained a Mexican Tourist Card from either a travel agent or a Mexican consulate prior to their departure. Additionally, if debarking with children, guests must have a notarized affidavit from any absent parent indicating permission to travel with the accompanying adult.
Special Notes:
1 - A photo I.D. is required of all guests 16 years of age or older. The photo I.D. does NOT have to be issued by a Driver's License Bureau or any type of Government office.
2 - U.S. and Canadian Citizens only - As long as the original birth certificate or the certified copy have been issued by the state of birth, it does not matter whether there is a raised seal of if the birth certificate is in the form of a plastic card.
3 - The name on the photo I.D. must be identical to the name on the proof of citizenship document. In the event of a name change, supporting documentation is required.
4 - Resident Aliens - Must surrender their green card at embarkation. It will be returned at Immigration check-in upon arrival back into the United States.
5 - Aliens (Non-U.S. Citizens) - Must surrender their passport at embarkation. It will be returned at Immigration check-in upon arrival back into the United States.
6 - For cruises that visit or transit Canada, citizens of some countries may require a Visa. This includes Alaska cruises and cruises from New York. Guests must check with the Canadian Consulate for documentation requirements.
7 - U.S. Resident Aliens and Aliens - Should contact the consulates of the islands/countries which they will be visiting to inquire about necessary travel documentation.