-Am Ex (good tip from the other thread) It's tempting to leave your wallet in the cabin. I am rethinking that.
Don't forget to put your card, along with your passport, ID, and other important documents, in a waterproof pouch. It would be a nightmare if you get to the consulate only to be told, "I'm sorry, sir, but we don't believe you are the real GarlyDog."
A map of the ship. Pay attention to exits and lifeboats.
Your flashlight should be waterproof.
Drawing supplies to draw Kate Winslet naked on your couch. (This could happen at some point after you escort her through the flooded, dark passages with your waterproof flashlight.)
Good thing I'm not a cruise sort of guy.