I know that there are dangers in using a debit card in many circumtances, but I have used a debit card for most of my 17 cruises, and a credit card for only a few. I have never had a problem or an overcharge.
However, in regards to debit cards, we used one at a local restuarant a few years back. This was a national chain restaurant. My DIL told us before we ordered that we should check our bank account if we used a debit card here. She had used hers there and they charged her bank account twice. Well we did not have the problem but a month later, our card was cloned. It was used on a Saturday in Atlanta - we live in South Alabama. We had a call from the bank's recovery dept that night and they said they knew we had used the card mid-day locally but that charges were popping up all over Atlanta. They took us for over $5000! We still had our card, it was just cloned. We finally got our money back but had to close the account. The bank recovery dept told us to never let our card out of our sight. If a waitress wanted to take our card to run it we should go with her, better yet stop at an ATM first and take cash to the restaurant. A few weeks later an acquaintance had the same thing happen and we asked if he had used his card at the restaurant and he had. Four weeks later his card was cloned!
Been there - done that:
2005 Holiday, Sensation, Conquest,
2006 Conquest, Celebration, Holiday,
2007 Freedom Grand Med, Holiday
2008 Fantasy & Sensation,
2009 Fantasy, Holiday & Dream Grand Med
2010 Fantasy and B2B Elation
2011 Monarch of the Seas
2012 Booked - Breeze from Barcelona 12 days