I’ve never actually been on a cruise, but I’ve read many comments about cruising and diving from others to let you know that most people try and sort out their own trip rather than a trip organized by the cruise line. The reason is that there is a better chance that the one they organize will only have a few divers on it unlike the cruise organized trip which will likely have all the people on the cruise ship, that want to dive being sent to one operator that is affiliated with the cruise line.