"I can't wait for my cruise so I can try all the healthy foods onboard," said no cruiser ever. Truth is, at sea there are endless junk food temptations. It's not easy to reject the buffet pizza, french fries and ice cream in favor of fruits, steamed vegetables and salads. (However, every cruise ship's main dining room typically features low-calorie or low-fat menu items, often labeled. You can also ask for a healthier preparation of a dish or a vegetarian meal; most chefs will graciously accommodate passengers' dietary needs.) But although cruise lines aren't making healthy dining options a priority, nutritious choices do exist for those able to resist the relentless calorie blitz.