"OK, I will suggest a few things: In Naples, be very very careful of your belongings, they rob you right on the street. No jewelry, keep your passport and money on your body, not in a purse."
I agree with Wanabee Quiltin. The pick pockets are everywhere in Rome. Enjoy your cruise. I went on almost the identical cruise a few years ago and I stayed an extra week in Rome. The cruise staff warned us about Rome and, thankfully, I had been warned by friends and had locks on my purse that were very visible. Our travel guide had her wallet taken out of her 'security' purse right in front of me on the train but fortunately another person right in next to me saw the incident and tackled the pick pocketer. She got her wallet back and the thief had just got off the train. Don't buy purses from the street vendors in Rome. It is illegal for the vendors to sell them and you, the purchaser, would be the one fined. The fine was $3,000 when I was there. I don't mean to scare you but want you to have a great time!