From Celebrity's website:
A gentleman's choice for casual nights includes a sport shirt and slacks, while women will be comfortable in a pants suit, skirt and blouse, or casual dress.
On informal nights, men are requested to wear a jacket, shirt and tie, while women may want to wear a suit or dress.
For the formal nights, including the Captain's Welcome Aboard Cocktail Party, dinner on the second night, and the Captain's Farewell Dinner held the next-to-last night of the cruise; both men and women may prefer more dressy attire, such as an evening gown for women and a tuxedo or dress suit for men.
The dressy sweater would be appropriate for casual night.
My husband wears his tux for formal, his suit for informal, and sports jacket and slacks for casual.
