Hi, I haven't been on a cruise before but I did just have a vacation at an all inclusive in Jan. I did cheat, but not as badly as I would have thought. I kind of approached everything with a "will this be worth it?" philosophy and other than white chocolate bread I was able to pretty much stay on Atkins. (The other cheat was tonic in vodka tonics. Who knew how many carbs tonic has!) I guess the trick will be just not having food in front of you constantly. Ours was an active vacation so this was pretty easy for me. If you do cheat don't be too hard on yourself, it was pretty easy to climb back on the wagon again after the vacation was over. Have fun!