it will depend on where you are travelling from i guess, and what nationality you are. if going from the uk (flying) each airine will have its own rules and you must check with them - ie driving liscence etc. If going by boat, i think the rules are less stringent., it would be worth while checking with whoever you are travelling with
i fly to jersey regularly,and evey airline i have used has always wanted a passprot to allow you through airport security, not for entering jersey,im told some may take some form of official photo id like driving licence,but have never put it to the teast.