Like others have said, it depends on the port. The navigator should tell you. Whether you take it or not, make sure you have a copy of it separate. If you take your passport, leave the copy on the ship and that way if it is stolen you can talk to port authorities and work with Disney (having a copy makes getting a new one easier). If you leave your passport, take the copy with you in case you miss the ship, same deal. I usually have a paper copy as well as a picture somewhere online (dropbox, emailed to myself, etc) where I can access it in case of emergency.