During the day, on any ship, the dress is casual. You must wear something over your swimsuits when in the dining rooms and other public areas. And shoes are always required.
The Lido buffet is always casual. The dining room is casual during the day.
A cruise can be divided into two or three types of dress codes for evening - Formal, Business Casual and Casual. Some ships are just calling it Smart Casual and Formal. And other ships are casual throughout. See below for descriptions.
The cruise brochure or your cruise documents should tell you the dress code. Your daily onboard newsletter will tell you the dress code for the evening and it applies throughout the evening.
Read up on the cruise line you're going on. If you absolutely refuse to dress up (husband won't wear a suit and wife won't wear anything but jeans), find a ship that is suitable. Don't get the attitude that "it's my vacation and I'll dress the way I want." Civilized behavior means there are times you will need to conform. If you don't like the atmosphere, find one you do as a courtesy to others. There are enough varieties of ships and cruise lines to accommodate everyone. Also, most ships have now opened up their buffet in the evening so people who don't want to dress up can eat there instead of the dining room on formal nights.
Here's what each of these dress codes entails:
Formal night: Men wear a tuxedo, dinner jacket or dark suit and always a tie. Ladies wear long gowns, cocktail dresses or flowing pants with beaded tops. Think of it as what you would wear to a formal wedding, a charity ball or a banquet. You can rent a tux onboard that will be delivered to your cabin (saving your having to pack it) at a very reasonable cost. They are even renting evening gowns for ladies now. Your cruise documents will contain an ad for this service.
Business Casual or informal night: Some ships require a tie and jacket, others just a jacket for men. Ladies wear pantsuits or dresses. Think of this as a business meeting or dinner in an upscale restaurant. Many ships have eliminated this category.
Casual night or Smart Casual: You can relax a bit on these nights. However, most have no jeans, t-shirts or shorts. Men usually wear slacks and collared shirts. Women wear slacks and a blouse. The first night is always very casual since you might not have your luggage yet and you are still in your traveling clothes.
If you don't have your bags yet and you've left port, don't worry. It takes a while to distribute all those bags. That's why you have your carry-on. Make sure you have what you need to get you through dinner on the first night. Some make-up, toothbrush, comb. Maybe even a change of clothes if you have traveled far and want to freshen up before dinner.
Also bring anything that's valuable or you absolutely couldn't do without plus the following:
Other things you might want to bring (not necessarily in your carryon):
Seasonal Alaska and some European Packing
June, July, August is normal summer wear with maybe a light jacket or sweater and rain gear. May & September are cooler months. If you're doing a shore excursion to top of a glacier (helicopter ride) or river rafting - Think layers. You can always peel them off as the temperature rises. To prepare for temps from 40s to 90s and probably rain, add:
If you forgot something, there are shops on board medium to large ships. Aside from the usual souvenir things they also carry sundries, books and some clothes, casual and formal. Of course there is also a jewelry shop and wine, liquor, tobacco shop. Liquor purchased for consumption on board ship is slightly higher in price than that for taking home. There are two price lists. American and foreign cigarettes are available but not an extensive selection. Anything purchased on the ship goes on your shipboard account, in US dollars.