Carnival will pass out your excurison ticket to your cabin. You need to have the tickets to join your tours. You will need to have your ship & sign card to get on & off the ship. Passport or birth-certificate are only needed when you re-enter US.
I agree, I take my D\L and "sail and sign" card as instructed..but is a very good question. As these requirements are changing 12/31/06, as far as U.S. But for re-boarding a valid ID and Sail and Sign is all that is required at this time. Personally I take what I call my "flippy" It is a slim wallet type thing with velcro that contains my D/L and S/S and the cash I need for the excursion, plus 1 credit card for emergencies.