I have worked on a few RC/Norwegian cruises over the last two years and before that my wife and I used to vacation on them frequently. Royal has a pretty decent dive program and some of the larger ships have a small dive shop that mostly sells Scuba Pro gear. Some people say they get good deals on jewelry and other things on cruises but I have ALWAYS been able to find things (worth buying) MUCH cheaper at home. As for dive shops where cruise ports visit frequently, I have found prices to be high here too. The same goes for dive gear on cruise ships. You will pay MSRP for your gear on a cruise ship. The reality is that they know you are on vacation and can't compare prices so they get you. You are also more likely to make crazy purchases because you are happy. Cruise ports rarely represent the island they are on anymore in a positive way. Cruise ports are designed specifically to suck the pod peoples (you) money and have evolved from that idea. Especially the electronic stores. If a jewelry shop or any shop (you won't find a dive shop on the list) is on the cruise ship list, it just means that they have been paid or have paid to be there. As others have said, buy before you go and try to book your diving with dive ops that don't service the cruise ship industry if it is possible. If you want to really experience the island/place you visit, then get as far away from the cruise port as possible, lol. Just a little honesty, have fun! Cruise ships can be really fun, but the more you know about it the less you want to be envolved with it. Being an eco-friendly diver and spending money on a cruise ship ....these things just don't go together.