Can you just use cash if you have no credit card on the Caribbean Princess for your sea pass?
You can pay for your sea pass account on-board Princess cruise ships instead of using a credit card, but a significant cash deposit will need to be taken upfront and added to your sea pass. This is around 300$ but you would need to confirm this with Princess. You then use the seapass/room key to spend on-board for everything apart from room service tips. A statement is then produced towards the end of the cruise and if you have money left from the deposit this is refunded back.