We've fielded quite a few inquiries about what to pack, so here's the official word from Carnival and some tips from some cruise veterans:

Formal dress includes tuxedo, suit and tie, or jacket and tie for men and evening gown, cocktail dress or pantsuit for women. Casual wear means sport shirts and slacks for men and dresses, skirts or pantsuits for women.  There are two formal nights per seven-night cruise.  For those not wanting to dress up, the Lido restaurants are open nightly and have a casual dress code.  Gym shorts, basketball shorts, beach flip-flops, bathing suit attire, cut-off jeans and sleeveless shirts for men are not permitted in the dining room during dinner.

I usually bring a pair of black pants and a black skirt and pair with different tops, scarves, etc. for the evening meal.  It's super casual the rest of the time!  Costumes are not required for the Polyester Power Hour Party and the Mad Hatters Party, but they make it way more fun!

If you have any other recommendations, please add your thoughts below in the Comments section.