Families have long been a bread-and-­butter market for the major cruise lines. But increasingly even niche players like river operators and expedition lines are angling to attract all ages.

“Something new we’re seeing is skip-­generation cruisers, where grandparents take the grandchildren,” said Michelle Fee, chief executive and founder of Cruise Planners, a travel agency.

She noted that the industry’s family focus extends from establishing infant playgroups to Royal Caribbean’s services for autistic children. “For families who have challenges, it’s a great vacation because it gives them a bit of a break and makes their child feel special,” she added.

The following innovations at sea range from family suites — with a slide between two levels — to educational programs that teach through play. All prices are listed per person.

Family-focused ship launches

Among the splashiest of ship launches, Royal Caribbean aims to abolish the bottleneck of ship check-in with its new 5,479-guest Symphony of the Seas. The ship uses facial recognition software to expedite cabin access on arrival.

That will get the children more quickly to the tallest waterslide at sea, the Ultimate Abyss, with a 100-foot drop. Families can spread out in the private Ultimate Family Suite, a bi-level cabin with an in-suite slide and a floor-to-­ceiling Lego wall. The ship will sail the Mediterranean this summer and transition to Caribbean voyages (from $374) in November.

Most of the family-friendliest ships tend to be deployed in the Caribbean, but the 4,000-passenger Norwegian Bliss will spend the summer in Alaska. It will have a two-level electric-car racetrack, a laser tag course and a water park with two slides, one that stretches over the ship’s side.

Your favorite characters

Special guests get a special welcome on a number of ships, including the new Carnival Horizon.

The 3,934-passenger ship hosts a Dr. Seuss-­themed water park, with slides based on the Cat in the Hat and Things 1 and 2. It also features a ropes course, a suspended bike ride called SkyRide, an IMAX theater and a 24-hour pizza and ice cream parlor. It debuted in Europe, but the Horizon will move to New York for the summer, beginning May 23, offering cruises to Bermuda (four days from $629) and the Caribbean (eight days from $759).

Disney Cruise Line introduced Marvel Day at Sea, offering daylong character interactions with Black Panther, Iron Man, Groot, Captain America and Black Widow on special sailings of the Disney Magic from Miami earlier this year. The event featured a live-action show and other Marvel-themed activities. Disney plans to repeat the series from January to March 2019. It offers similar “Star Wars” at Sea events.

Clubs and baby-sitting expand

Kids on board have more opportunities to meet their peers, while parents have more date-night options.

Princess Cruises has redesigned its youth and teen clubs, including a treehouse-themed hangout for ages 3 to 7, an outdoorsy lodge for those 8 to 12 and a beach house for teens 13 to 17. Activities focus on science, creativity, play and socialization. Currently on five ships, the new clubs will be rolled out to the entire fleet through 2019.

Celebrity Cruises’ Camp at Sea program offers activities for children 3 to 12 along four tracks: art, recreation, culinary and STEM. The line offers late-night “slumber parties” between 10 p.m. and 1 a.m.

In April, Norwegian Cruise Line sent the Norwegian Escape, featuring four waterslides and a three-story ropes course, to New York for weekly cruises to Bermuda (from $629). The ship is the only one in Norwegian’s fleet to offer child care for children from 6 months to 3 years old.

Education at sea

Expedition ships are adding educational programming that aim to make science fun.

This summer, Lindblad Expeditions plans to extend its National Geographic Global Explorers program to Alaska. Launched in the Galapagos last year, the program encompasses science, exploration and storytelling, including learning to drive an inflatable vessel, spot wildlife and create time-lapse videos. The program will be available on the line’s three ships in Alaska (five nights from $4,290).

In the South Pacific, Paul Gauguin Cruises is teaming up with the nonprofit Wildlife Conservation Society during the summer months to offer nature-focused educational activities for children 7 to 17. The programming includes naturalist-led snorkeling excursions, shipboard stargazing and dolphin watching (seven-night itineraries from $5,845, including airfare between Los Angeles and Tahiti).

River cruises for all ages

With their port focus and lack of whiz-bang amenities, river cruises generally appeal to adult travelers, but AmaWaterways has joined with Adventures by Disney to offer 16 themed sailings in 2018 that include “Beauty and the Beast” itineraries on the Rhine River, featuring castle visits and film screenings (eight days from $6,139 for adults). It has also enlisted the active travel company Backroads to bring biking, walking and hiking tours to more than 60 sailings aimed at multigenerational sailors.

Avalon Waterways’ active cruises cater to travelers age 8 and up. Its new active itinerary on the Rhine between Frankfurt and Amsterdam includes options to bike, hike and run (eight days from $2,149).

Uniworld Boutique River Cruise Collection offers the Generations Collection cruises for families. Its new Rhine itinerary takes visitors between Basel and Amsterdam, and includes pedal boating, a castle treasure hunt, bike riding and zip-lining. Designated staffers oversee children’s activities, including cooking classes, craft workshops and movie nights (nine days from $3,519 for adults).

Multigenerational adventures

Cruise lines that don’t specialize in families still welcome them with activities positioned as multigenerational draws.

Normally, children must be at least 8 years old to sail with UnCruise Adventures, which focuses on wilderness destinations. But this summer, the 86-passenger S.S. Legacy will sail to Alaska and drop the age minimum entirely on two departures (seven nights from $3,995). Skiff excursions offer wildlife watching up close.

One Ocean Expeditions will offer two summer sailings around Canada’s east coast, reaching some remote areas such as Sable Island and Gros Morne National Park in Newfoundland. Aimed at adventurous families, the 10-day trips include sea kayaking and whale watching (from $3,395).

Regent Seven Seas Cruises will deploy its refurbished Seven Seas Mariner to Alaska this summer. The 700-passenger ship employs two counselors to oversee children’s programming for ages 5 to 12 and 13 to 17 when the ship is not in port. When it is, most shore excursions — a selection of 44 offered over a weeklong trip — are included (seven-night trips from $4,899).