Cruise line private islands and what they offer passengers 

Touring rum factories and butterfly farms, hiking to a waterfall — there are many ways to stay busy on a Caribbean cruise. But sometimes, all a passenger wants is a beach day.

Cruise lines have received the message. They’re spending millions on private island destinations that entice passengers with pristine beaches equipped with every necessity, lavish barbecues, and private cabanas.

"Most of the cruise lines have had private islands since the '90s," said Gary Tarlov, of Embark Nation, a Long Island-based travel agency. Over the years, he said, the lines have added more islands and upgraded the facilities as they’ve become so popular. "It’s a great diversion from stopping at ports or sea days," he said, "the perfect way to chill out on the beach."

Amenities are similar on most of the islands, with plentiful food (emphasis on Caribbean favorites like jerk chicken), bars wherever you look, expanses of white sand beaches dotted with umbrellas and lounge chairs, many with separate areas for adults and kids. For those who can’t sit still all day, activities range from paddleboarding and snorkeling to serious water parks and intriguing excursions (swimming with pigs is a highlight for many travelers on one island).

Guests can spend the entire day at most of these destinations without spending another dollar, though there are additional charges for extras like water parks, excursions and upgraded areas (nicer lounge chairs, lobster instead of burgers for lunch). Costs skyrocket for private cabanas, which range from cozy seaside shacks with plenty of shade and a few lounge chairs to ultra-luxurious villas with air conditioning, bedrooms, outdoor showers and server service.

Here’s a look at highlights on several of these islands.

Perfect Day at CocoCay

Cruisers on Royal Caribbean and Celebrity often say their day at CocoCay is the high point of the trip. The milelong Bahamian island offers many enticements to get guests out of their beach chairs — a giant helium balloon provides an impressive bird’s-eye view and there’s a water park with nine slides (the 135-foot Daredevil’s peak is the tallest waterslide in North America). Other family-centered activities include a zip line and an obstacle course in the huge freshwater pool.

"It was perfect for us," said Denise Butler, of Levittown, whose family visited CocoCay in June while cruising on Symphony of the Seas. "We considered it a beach day," she said, explaining that her family got there early to stake out a spot near the water. Butler said she was a little disappointed that extras like the water park were so costly. Still, she said, "We found the day relaxing." Smart travelers, they left CocoCay right after lunch and went back to the nearly empty ship, where they found no lines for the usually crowded waterslides.

Cost A four-night cruise on Liberty of the Seas is about $670 inside, $1,045 balcony (note that cruise pricing is fluid, for this article, we checked in mid-September for the lowest cost cruise that stops at a private island). Cabanas start about $299 and go up to about $2,500 for one of the fancy floating cabanas (which come with a slide and overwater hammock).

More info royalcaribbean.com/cococay-cruises

Lookout Cay at Lighthouse Point and Castaway Cay

Celebrating the Caribbean culture is the highlight of Lookout Cay, Disney’s newest private destination on the southern tip of Eleuthera, which greeted its first guests in June. The Goombay Cultural Center offers lessons in making things like lavish feather headpieces, which you can then wear to "Rush! A Junkanoo Celebration," a twice-daily showcase of traditional music and dance.

On Castaway Cay, the original Disney island that’s been around since 1998, guests are immersed in some theme-park make-believe as they’re thrown into a story about castaways on a deserted island. Mickey and Goofy make regular appearances and visitors can participate in a 5K run.

Emphasizing environmental concerns, Disney programs include restoring the coral reefs, monitoring endangered loggerhead sea turtle nests and using recycled cooking oil to power some vehicles.

Cost A three-night cruise on the Disney Wish with a stop at Castaway Cay starts at $1,939 for an inside cabin for two; a balcony starts at $2,215. Cabanas start about $500 on both islands.

More info disneycruise.disney.go.com

Great Stirrup Cay

A U.S. military installation once stood on this 268-acre island, now the private island destination for the Norwegian Cruise Line. There’s plenty of room on several beaches, but for a more luxurious experience, there’s Silver Cove, where air-conditioned villas on a quiet lagoon offer server service, on-demand movies, a full-service buffet and even a branch of the ship’s Mandara Spa.

For many visitors, the highlight is an excursion to swim with a bunch of feisty pigs. That’s been a thing in the Bahamas for a few years, but it’s easier from the island — it’s just an invigorating boat ride to Treasure Island, where the resident pigs await. After a brief orientation, guests hit the water, enticing the friendly animals with apples on a stick.

Cost A three-night cruise on the Joy starts at $828 for an inside cabin, $1,328 for a balcony. Cabanas start at $599, Silver Cove villas, $1,299.

More info ncl.com/freestyle-cruise/great-stirrup-cay

Princess Cays

Eleuthera is 100 miles long, meaning it has room for two cruise destinations. On the southern tip sits Princess Cays, with a half-mile beach and plenty to do including a stingray encounter, snorkeling, banana boats and other water activities including an observation tower with expansive views.

The barbecue is free, but you have to pay for almost everything here — umbrellas (from $34.95) and shaded cabanas known as clamshells (from $44.95), even pool noodles cost $4.95.

Cost A seven-day cruise on the Sky Princess starts at $1,338, inside, $2,018 balcony. Bungalows start at $239.95, and go up to $319.95 in the adult section.

More info princess.com

Half Moon Cay

Carnival and Holland American ships stop at this island, Little San Salvador. Most people head straight to the beach, where lounge chairs are free but umbrellas and clamshells must be rented. Horseback riding is a prime activity on Half Moon Cay, and the horses are happy to take riders into the warm Caribbean waters. The island’s fanciest cabanas are partially over the water and come with a personal chef who will prepare a barbecue lunch, a steward and your own lifeguard.

Cost A four-night cruise on the Carnival Conquest starts at $638 for an inside cabin, $1,079 for a balcony. Cabanas start at $499.99, Private Oasis cabanas start at $1,849.99.

More info carnival.com