It can be really easy to overpack for your first cruise because you don't know exactly what you'll be doing and what you'll need. There's a lot of generic "cruise packing" lists going around, and I wanted to share my thoughts on some of these as someone who has been cruising since jr. high and is planning her 9th cruise:
Related: Cruise packing favorites
Laundry soap
You'll see a lot of packing lists recommending you bring a small thing of travel laundry soap for your cruise so you can do a load of laundry in your sink. I'm convinced that anyone who includes this on a packing list has never actually used it. Cruise bathrooms are small and the sinks are not deep at all, so I don't think you'd be able to actually wash your clothes and get all the soap out. Instead, bring a Tide To Go pen to spot-treat stains. You also likely won't even need to wash your clothes on your trip, unless it's longer than a week cruise. If you really need to do a load of laundry, the ship will usually have a wash and fold service for about $30.
Clothes line
Another thing I see recommended a lot is a clothes line to air dry swimsuits and wet clothes in your room. While this is a great idea, and even I air-dry my clothes on a clothes line on cruises, you don't need to bring your own. The shower in your bathroom will have what looks like a little bell, but is a retractable clothes line.
The only time I would recommend you spend your hard-earned dollars and take up precious packing space in a suitcase by buying and bringing your own clothes line is if you have a balcony cabin and only 1 swimsuit. If you only have 1 swimsuit, then the wind and sun from being outside will dry your only swimsuit fast enough for you to wear each day. But, if you bring at least 2 swimsuits, yours will dry in plenty of time on the shower clothes line. Personally, I prefer to bring a swimsuit per day on my cruise, because it's my main "outfit" each day.
Hidden document or money holders
Unless you're traveling to Europe, you just won't need an under the clothes document holder or a money belt. First of all, these are actually really impractical to use. My dad took a money belt on our first cruise, and it seemed like his money would go everywhere when he'd try to pay for something. I've also seen people struggle to get their passports out from their under-the-shirt document holder, and it's not a pretty sight watching them fish that out from under their shirt, half flashing everyone as they do.
I don't get off the ship with my passport because I personally feel that at each stop I'll have a larger risk of losing my passport somewhere at the port than missing the ship or having some other emergency where I'm stuck at the port without a passport. I do have a scanned copy of our passports saved in a Goggle drive that I've made available offline, just in case.
Instead, I recommend a waterproof travel wallet. These zip up to keep money/cards from falling out and to keep it waterproof. It's perfect because all you need at port is your ID, your ship card, a credit card, and some cash for tipping/bartering/buying things from merchants on the beach, so you can leave everything else in a regular wallet in your stateroom safe. If your wallet gets lost/stolen, then you didn't just lose all the cash you brought for the trip and all of your credit cards. Or, if you need a safe place to store your passports or other large items, you can get a crossbody bag that keeps your stuff right on you so it can't get lost/stolen, but is much easier to access.
A ton of shoes
If you're just going to the Caribbean, then you actually only need 3 kinds of shoes: closed-toed shoes (like sneakers) for on-board activities like basketball and the ropes course, and for shore excursions like parasailing and horseback riding; sandals/water shoes for the beach, and heels or dress shoes for dinner. That's it!
One of my favorite packing tips for cruises are Pasion Footwear shoes! You might have seen them on Shark Tank, but they are sandals that can convert to heels, and the heels are interchangeable. So, I just wear them as sandals around the ship during the day, and then I have the 3" espadrille heels for most dinner nights, and 4" rhinestone heels for formal night.
Black tie formal wear
Formal night is a lot less "formal" than you'd expect if your only experience with a cruise is Titanic. You don't need to rent a tux or bring a ballgown for formal night. On our first cruise, I wore a prom dress and felt way overdressed. Most people wear suits and cocktail dresses for formal night.
Printed out deck plans
There is no need to print out and laminate the deck plans before your cruise. At each elevator there will be a display of the ship showing what is on that particular deck, plus a list of what is on each floor. The deck numbers in the elevator will also have the main stops listed out by each deck. And, your cruise will have an app that will have detailed deck plans, so there's no need to carry printed plans around with you.
Binoculars
The only cruise that you might need this is Alaska. Every other cruise, these probably won't be used.
Camera
Unless you're really into photography, it's just easier to stick with your phone. Remember, some days you'll be getting off the ship at 7am and not returning until 3pm, so you'll be stuck carrying it around (and watching to make sure it's not lost or stolen) all day. Plus with a camera you'll need to bring extra cords to charge it and other accessories that will eat up space on the tiny desk you have in your room.
Any iPhone 7 or newer is waterproof, and basically any Android will be waterproof too, so you can take your phone with you anywhere and get really good pictures. If you're worried about holding onto your phone when you're in a swimsuit and don't have pockets, or if you want to swim around in the ocean, you can put your phone in a waterproof phone pouch and just wear it.
Same goes for a digital clock or night light, even if you're in an interior cabin. Instead, I would bring a good smart watch. Not only will this also will this have the time and a built-in flashlight, but you can use it all day long. I add our daily activities and itinerary to my calendar, and then my watch lets me know what's up next and where. It's also really helpful if you're traveling through time zones on your cruise. Ship time is always the time zone of where you embarked for your cruise on day 1, but your phone will likely switch over to local time when you get there. There's always someone on each cruise that gets in a bind because they don't realize that the time on their phone is different than ship time. With a smart watch, you can have 2 clocks on one watch face, one for local time and one for ship time, and it will keep you on time all day.
Guidebooks
Maybe if you're going to Europe and you don't have an excursion or tour planned, this might come in handy. Other than that, I don't think you would need this. Many of the ports are not in the main city in the country, so a lot of the recommendations might not be geographically feasible for this trip.
Physical books
Not only are books heavy for you to carry and keep up with all day, but cruises are often wet. Kids splash in the pool, it inevitably rains intermittently, the deck is often wet from being recently cleaned, the waves will spray water towards the beach, drinks get spilled... you get it. There's just too many chances for your book to get ruined. I only bring a waterproof Kindle with me and it's great because it's lightweight to carry and I don't have to worry about it getting wet. I just make sure to pre-download 2-3 books before my trip so I don't have to worry about trying to connect my Kindle to the ship wi-fi and waiting forever for the book to download.
