Leave the snacks at home (as well as water). There is plenty of low carb foods to choose from. Worst case scenario you will not get what you want in the restaurant and will have to go to the buffet where you have more low carb choices. Some ships (especially European lines) don't let you bring water by cases any longer as they prefer to charge you for bottled water. Bring the bottle with you and refill if you do not want to pay extra. And by the way get prepared to gain a lot of water weight. I do not know what they add to food but it usually takes me a week to get rid of it.
The first thing you lose on a diet is your sense of humor. ~ Author Unknown
It doesn’t matter what diet you follow… What matters is what makes you follow your diet. ~ Tom Venuto