They do not like jeans in the dining room at night, during the day it's fine. If you stick to trousers and a polo or shirt on non-formal nights, you'll be fine. A pair of dress slacks with a dress shirt, jacket and tie are fine for formal evenings. A tuxedo is up to you. Since it's your honeymoon, you might want to go all out and get some great pictures of you and your new bride. The photographers are everywhere, but they do a fantastic job on their portraits.
Congratulations! It's a wonderful way to start your lives together. Just a warning, cruising is addictive