Passport?
 

Can anyone tell me what is required when cruising with a baby...i.e. does the baby need a passport or is a Birth Certificate sufficient?

It depends on the cruise itinerary. If it is a closed loop cruise then the baby's original birth certificate will suffice. If it is not a closed loop cruise, then regardless of age a passport will be needed.

Look here for the definition of a closed loop cruise.

Thanks Dave...we were getting nervous since we just thought of this and we cruise in 2 weeks!

You should have a passport for the baby no manner what. If you have to return home from one of the ports you will be out of luck as the baby will not be allow to get on a plane. Passports are the safety and secure way to travel. My family have always gotten passports even when everyone was a baby.

Key word is original. A state-certified copy (with official seal) will also be OK, yet the original one from your state is the best. A hospital certificate will not do. Read more here: Required Cruise Travel Documentation & Information | ID, Passport ID & General Documentation | Norwegian Cruise Line

When you return, I strongly suggest that your get a passport for the baby. It saves a lot of hassles and also provides peace of mind.