Hi there! Happy 10th!
I cruise regularly (1-2 a year) and while I allow myself to indulge a but, I also exercise a LOT. Last year I lost 2 pounds when I came back! I never felt deprived (even had a slice of pizza, frozen yogurt and french fries) but I ate within reason and was sooo active (we did snorkeling excursions) - we also hit the gym 2-3 x during the trip.
It's so doable to indulge and have fun but not go too crazy! We're doing the chef's table this cruise in April for my MIL's 60th and I am going to indulge in whatever they cook me
Have a blast! Where are you going and what cruise line?