Private islands operated by cruise lines are beautiful patches of vacation paradise with white sand beaches, lounge chairs for everyone, refreshing tropical drinks that come to you and activities such as water sports and zip lines. Don’t create trouble in paradise by making an epic vacation blunder that will leave you with beach-day regrets.

These 11 common mistakes trip up both newbies and experienced cruisers alike when visiting popular private islands on Caribbean and Bahamas cruises. Be forewarned so you can live out your island fantasies without a single travel nightmare.

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Some vacationers new to cruising do not consider themselves “beach people” and assume that there is no reason to go ashore at a private island. The reality is that island days are not only about sitting on the beach, and you're missing out if you stay on board.

Tours on the water abound, whether you want to explore via kayak, glass-bottom boat or jet ski. You can wade with stingrays or go fishing. In some locations, you can even take tours to nearby islands.

For example, on Carnival Corporation’s Half Moon Cay, a popular attraction is horseback riding in the surf. Tours of the island’s farm include learning about local plants and agriculture. Nature hikes go to ruins of limestone fishing huts from the late 18th century and places where you can spot the island’s nesting seabird population.

On Royal Caribbean’s Perfect Day at CocoCay, you will find over-the-top attractions such as the tallest waterslide in North America and the largest freshwater pool in the Caribbean, plus zip lines and helium balloon rides.

For all tours, advance bookings are required.

Related: The 10 best beaches you can visit on a cruise

Your cruise line’s private island may be bigger than you think. It can be a long trek on boardwalks or sandy roads to the beach from where you disembarked the ship or tender. Don't make the mistake of walking to the far end of the beach with all your gear when the cruise line will provide open-air trams to take you where you want to go.

If you are looking to stretch your legs on purpose, check the island map for suggested hikes or rent bikes to explore on two wheels. (You’ll likely need to make reservations for bikes in advance.)

It’s human nature to grab the first empty beach chair you see, but if you pick a lounge chair close to the pier, you'll be in the noisiest, most crowded part of the island. Keep in mind that more than one ship can visit a private island at the same time, so those empty spots near you will fill quickly. Walk away from the ship (and the music-blaring bars) and you will be rewarded with more peaceful surroundings.

In addition, some islands have more than one beach, so don’t settle for the first one you find. Disney Cruise Line’s Castaway Cay, for instance, has beaches earmarked for families and teens plus Serenity Bay, a heavenly mile-long stretch on the north side of the island that is reserved for adults.

Tip: If you’re planning to snorkel from the beach, you also will want to get away from the crowds for a more undisturbed look at marine life.

Related: Caribbean vs. Bahamas cruises: Which itinerary will I like better?

Cruise lines rent private open-air beach (or pool) cabanas for hundreds of dollars per day and private air-conditioned beach villas for more than $1,000. These exclusive retreats get you VIP treatment and extra perks on your private island visit. Despite the high price tag, they are highly sought after and sell out fast.

The key here is to book these havens — if you want them — as soon as you have paid for your cruise in full, since they sell out fast. Priority may be given to suite guests. Procrastinate and your dreams of relaxing on an uncrowded beach or getting lunch served by a butler will likely be dashed.

On your cruise line private island, you’ll find shacks stocked with a limited number of floating beach mats, snorkels and fins, kayaks, stand-up paddleboards and other water toys. To ensure you get what you want, reserve the equipment before your sailing or while you’re still on the ship. You don’t want to be that parent who has to tell your kid there are no more floats available.

Related: The best Caribbean cruise for every type of traveler

Cruise lines promise free lounge chairs on their private islands but they don’t guarantee fee-free shade. If there are beach umbrellas on your cruise line’s beaches, they may or may not be free. Clamshell covers for lounge chairs always cost extra and are best reserved in advance because they often sell out.

A free option is pulling your beach chair over to the shade of palm trees, where you may also find hammocks. However, these shady spots may already be claimed by clamshell rentals or only accessible if you trek all the way down the beach. That said, you can always escape the sun in shaded bar and buffet areas — though they’re not necessarily the most scenic spots for lounging.

Some people head off the ship in the morning, get bored by noon and go back to the ship for lunch. These folks miss the fun of having lunch at picnic tables or taking their meals to their beach chairs. Yes, we know sand may be involved, but it’s still an experience.

If you've never sampled the fare at a private island barbecue, it's a mistake to skip this alfresco dining opportunity. Depending on the cruise line, you’ll find grilled burgers, hot dogs, jerk chicken, ribs, steaks, corn and an assortment of salads, desserts and fresh fruit, all served buffet-style from an open-air pavilion.

Also, don't make the mistake of assuming lunch on a private island is always the same. Carnival Cruise Line and Holland America both send ships to Half Moon Cay, but the sister cruise lines offer very different beach barbecue menus from each other, and both are worth a taste.

Related: Cruise ship restaurant nirvana: The 7 best meals you can have at sea

While the island barbecue is a staple of the private island experience, some destinations offer alternative lunch options that shouldn’t be ignored. Make sure you know about all your food choices before digging in because you might miss out on a special meal.

For instance, Holland America Line has a venue serving up grilled lobster and conch stew for a fee. Norwegian appeals to gourmands with complimentary food trucks serving tacos, ceviche and pulled pork sandwiches. On MSC Cruises’ Ocean Cay, you can buy a lobster roll and indulge in ice cream served in a cone shaped like a fish (also for a fee).

Royal Caribbean’s Perfect Day at Cococay offers three Snack Shack outlets, an a la carte menu at Captain Jack’s bar and a restaurant exclusive to cruisers who pay for access to the Coco Beach Club, in addition to two complimentary barbecue venues.

To maintain the beaches and other facilities, your cruise company may employ dozens of staff who live on the island along with locals who come over to work for the day. Their village area, which includes a kitchen, power generator, water and sewage plants, recreation hall and other facilities, will be marked as private. Treat this area like someone’s home and stay out.

That said, if you’re curious how a cruise line runs a remote island playground, you may be able to book a back-of-the-house tour to see how the private island operates.

Don't spend tons of money on rentals when you are allowed to bring your own snorkel gear to a private island's beach. A family of four could save $120 or more in rental equipment fees with a BYO approach. Plus, you can ensure that your masks fit properly and not have to worry about the cleanliness of shared equipment.

If you have room in your luggage, you may also want to pack the kids’ buckets, shovels, sand toys and beach balls so you don't have to listen them whining about having nothing to play with or begging you to buy beach toys at the island’s shops. Inflatable balls and floats pack down flat for easy transport and keep the kids entertained while you relax on ashore.

Related: Best cruise line private islands for families

If you hastily toss a few things in a beach bag five minutes before heading off the ship, you’re bound to forget something important. Take time to pack all the beach necessities so you’re not stuck paying inflated prices at the straw market on island.

Sunscreen, sun hats and sunglasses are a must. You might also want a cover-up when you head to the lunch barbecue and either water shoes or closed-toe shoes for specific excursions. On some lines, you need to bring a pool towel from the ship to use on the island; don’t assume towels will be provided.

You may also want to have a few dollars on hand to purchase souvenirs at the straw market and for tipping island staff (especially if you’ve rented a cabana with an attendant).

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