From NCL's FAQ
What Should I Pack?
To give you an idea of what to toss into your suitcase, we've got answers to some of your questions like:
Can I wear something casual to dinner?
Do people dress up at night?
Can I wear my swimsuit day and night?
The answer to all the above is "yes" - with Freestyle Cruising, you're pretty much welcome to wear whatever, whenever. Our philosophy is "resort casual" and with the widest range of dining venues, tons of entertainment options and bars & lounges, you'll find there are places for your style all over our ships, day and night.
Daytime, it's basically all fine since we know you're probably headed to the pool or out for a fun Shore Excursion. Casual shorts, jeans, tops and sundresses are welcome everywhere. You can even wear your swimsuit to the poolside grill or the buffet.
Resort casual dress gets you into every venue at night too. Some people like to add a jacket, or when celebrating a special occasion, get all decked out. This too is welcome everywhere. And if you're tired from a long fun day and just want to wear shorts; our buffet is the place for a casual dinner. Some people prefer nice jeans. They're welcome in many of our restaurants as well, but not in all. It's your vacation on NCL so dress comfortably, and you'll find a venue that suits your style.
Since all suitcases are collected the night before we return home, don't forget to bring an overnight bag packed with a change of clothes, prescriptions and need-to-have items. Thanks to Freestyle Disembarkation, you'll have time on your final morning on board for breakfast and some last minute sunbathing or even a workout.
Well, that's NCL's answers.