This is not about the clothes to pack, but additional things.
Passport
While many cruises don’t require one. We always recommend it if you are going to any ports outside the US. This is because anything could happen. If you must fly back you will need a passport.
Also, you could consider a waterproof cover for it. I like to put all our passports into a Ziploc bag. This keeps them all together for when they are needed, and keeps them dry just in case.
Suitcase
Ok, I know you don’t put a suitcase in a suitcase, but have a reliable suitcase on wheels, with a good extendable handle that works. A hard case is good for keeping your stuff stays dry. After all, if it is raining on the day you leave or the day you return, those suitcases could be sitting out in the rain soaking in the water.
Many of the hard case designs have expansion zippers for those purchases you make easier to pack.
Water Bottle/Travel Mug
A no-spill, vacuum insulated coffee cup or bottle helps to keep beverages hot or cold. When it’s hot it’s important to stay hydrated. Your own mug/bottle makes refills easy, too.
Portable Clothesline
Your bathing suit and wet shorts from swimming and any excursion where you get wet, need to dry overnight. While some ships have a clothesline in the tub, not all do, and sometimes you need more line. Also, you may need to take some clothespins?
Underwater Camera
Not only does it allow you to take underwater pictures, it means you don’t have to worry about if you get your camera wet.
Portable hand held fan
If you are like me, who likes the weather warm, you may not need it, but you can enjoy a bit of coolness with a handheld portable fan. This mini gadget is easy to take anywhere and doesn’t cost much either. You can take them along with you where ever you go – be it beach, shops, or dining.
Ziploc bags
As I explained about our Passports, the same holds true for anything. If you have a bottle of lotion you need to take, if it is in a Ziploc bag, it won’t ruin all your clothes you packed in the same suitcase if it leaks. It also helps keep all your little stuff together so it doesn’t get lost. Plastic bags come in handy as waterproof “cases” too.
Hat
Having a good collapsible hat (big sun hat or ball cap) can come in handy to shade the sun.
Sunscreen and Mosquito Repellent
Sunscreen is a no-brainer, but sometimes that bug repellent is forgotten.
Waterproof Jacket
Find one that’s thin enough to fold so it doesn’t take up much space. You may think it would never rain on your vacation, but almost every cruise I have been on there has been at least one day of rainy weather. If you don’t want to give up your outside sight-seeing for the one time you are in port, consider a rain jacket or poncho.
A Good Attitude
Ok, you’re going on vacation, and all you think is it’s going to be great! Well, sometimes things happen on vacation. You could be delayed, your bag gets lost, you forgot something, etc. Remember, to have fun and don’t get overly concerned about things that happen. You’ll look back and wonder why you got so upset that you forgot your sunscreen, especially since you will find you can buy it someone along the way – maybe even on the ship.