https://www.msccruisesusa.com/en-us/Manage-Your-Booking/Web-Check-In.aspx

MSC web check-in allows guests to check in anytime up to 24 hours* before the day of departure.

United States citizens on a roundtrip cruise departing from one United States port, sailing within the Western Hemisphere and ending in the same United States port can use a government issued picture ID along with proof of citizenship in the form of an original or notarized government issued birth certificate or original Naturalization certificate in lieu of a passport. 

What you'll need for Online Check-in:

  1. Your cruise line confirmation number, ship, sail date (this will be on your Cruise Brothers Confirmation)
  2. The full legal name, date of birth for each traveler in your party
  3. Passport or appropriate travel documentation information for each traveler Passport #, date of expiration, date of issue
  4. Emergency Contact name and phone # (this is someone not travelling with you)
  5. A credit card - this is used to set up your onboard account – Cruises operate on a cashless system and do not accept cash for onboard purchases and gratuities.
  6. Travel plans before and after your cruise. They want to know how you plan to get there and how you plan to leave.