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, the 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.