I usually take a couple hundred dollars to use on shore when the wife goes shopping. Being a cop, I NEVER use a credit card in another country; too many variables run through my little pea brain. IF you need extra cash, you can obtain it in the casino (for a small fee) and have it put on your sea pass account. I'll take large bills ($50's or $100's) and then use the service desk or casino to break them down as needed. On the ship, you will not need cash except to place it in the Tip envelopes. I always pay the cruise line for any excursions ahead of time using a credit card; however, if I find something once onboard the ship, the costs can be added to your Sea Pass card. There are others on this site who use local merchants for excursions, which is fine since sometimes they are cheaper. I LIKE being a citizen of the USA and don't want to take the chance of missing the ship and becoming another country's member, so I book through the cruise line. I will admit the I have only cruised on RCCL, so I only am familiar with their policy of leaving you behind when the ship sails, not another cruise line's policy. If they are different, someone here will let you know. This is ment to be a FUN time on a cruise. Allow your "careful meter" to be a little more sensetive, and relax. Have a Great Cruise!!