Read over the US passports website and I'm still not sure of the answer to my question. Anyway - I have a 4 year old and 22 month old (at time of cruise)...initially I thought I'd be ok with just birth certificates, but then I saw something on the passport site I believe saying that some ports will not let kids get off the boat if they do not have one. We are going for 4 nights on the Dream to the Bahamas, stopping in CC and Nassau. Do they need passports or not? Also, are passport numbers needed for online check in? Our online check-in registration thing starts next week, and my dad just renewed his passport and it hasn't come in the mail yet. Thanks in advance!