The only cruise I've ever been on that had vegan food as a matter of course was Celebrity. Unfortunately, this was before RCI bought them out so I have no idea what their vegetarian meals are now. At the time they always had two vegetarian entrees for dinner, one ovo-lacto and the other one vegan. They were delicious, every bit as good as their regular meals. At lunch there was always something bean based and breakfast was usually cereals and breads. The only thing I would urge you to do is to bring along individual cartons of either soy or rice milk. I've never seen that offered by a cruiseline.