We just got back from a cruise on the Grand Princess. While in Grand Cayman we did the snorkel/Stingray City thing with Captain Marvin. I read another review where the person did Captain Bryan. I think that person makes a good point about the clean quiet Cat vs. noise and smell of the diesel that Captain Marvin uses. HOWEVER, when we went there were only 10 people on the Captain Marvin boat and the Captain Bryan Cat was PACKED. Everyone on our boat commented how lucky we were to be with Captain Marvin. We had a great time and the two guys from Captain Marvin went way out of their way to make sure everyone got a chance to feed and play with the stingrays. Captain Marvin also had a diver on-board that did a underwater video of the whole excursion. While his price for the video was high ($45) it has served as a great memory of the event. Bottom line, Captain Marvin gave us a great experience and I would use them again if I get back there.