Just went on the Holiday 4-19-04. Had an inside cabin on the upper deck. In order to use the safe, all you have to do is put in 4 numbers for it to close, and open. You do not use yur sail & sign card as on other Carnival ships. Also, you will get a separate coded key for the cabin door, the sail & sign card does not act as your key on the Holiday. I would assume all the safes on this ship would work the same way.
Have a great cruise. I did!