With so many Disney, as well as Pixar and Marvel, characters, it's no surprise that the Disney Cruise Line experience is centered on character-driven activities. Guests can enjoy character-based theater shows on all of the ships — one is a mix of different Disney villains, for example — and there are at least a half-dozen character photo ops every day.
Highlights: The line offers Royal Tea and "Star Wars" Day at Sea on Disney Fantasy, and the "Frozen" Deck Party on Disney Magic and Disney Wonder. Disney Dream just received a "Star Wars"-themed area in its children's playroom, complete with a Millennium Falcon cockpit.

Royal Caribbean has teamed up with DreamWorks Animation to bring characters from popular films to sea. Kids can hang out with characters from "Shrek," "Madagascar," and "Kung Fu Panda" (among others) at meet and greets, meals, and events. The DreamWorks Experience is available on eight of the line's 25 ships. 
Highlights: Look for a "How to Train Your Dragon" ice show on ships with ice-skating rinks.

Carnival has brought Dr. Seuss stories to life with Seuss at Sea, offered on all of its ships. With a character parade, interactive story time, and other Seuss-inspired activities, little guests are sure to have a good time.
Highlights: Start a day at sea with the Green Eggs and Ham character breakfast. (Just be sure to try the actual green eggs.)

MSC has partnered with LEGO to give kids the LEGO Experience. Look for DUPLO bricks for toddlers, a wide array of LEGO toys for older kids, and a variety of shows and interactive building experiences. The LEGO Experience is currently offered on MSC Armonia, MSC Sinfonia, and MSC Opera.
Highlights: On these ships, the LEGO mascot, Sailor Walk About, hosts a talent show and meet and greet for kids.