We spent a week on the island diving with Stuart Cove's. They are on the opposite end of the island so I doubt that this is the dive op that Disney uses. If it were me I would stick with the Disney excursion. I know that others have booked their own dives and they may get a better dive for an experienced diver but I would stick with the excursion. With the excursion you don't have to worry about where to go and when to be back they will lead the way. You also don't have to be concerned with a change in itenirary due to weather which you may have to if you book your own trip. I have taken 4 scuba excursions with 3 different crusie lines in the last few years and I would say they were all very good, none bad and none great, but all were good. It was a lot less hasel to use the cruise line excursions than booking my own trip.