A Variety of Programs
With this boom in youngsters on board, most cruise lines not only are providing more facilities and personnel to youngsters, but also expanding and refining their children's programs, particularly on their newer ships.

Pretty much gone is the old concept of the children's center as simply a babysitting operation. Today's youngsters are offered a smorgasbord ranging from strictly fun and games to sophisticated educational opportunities.

Dissecting a squid, for instance, is part of Princess Cruises' science program on Coral Princess, along with rocket-building. The line also partners with the Miami Seaquarium on a series of videos about and activities related to Caribbean marine life.

On sailings aboard the new Carnival Conquest, youngsters learn about island culture and geography as part of the line's extensive EduCruise program, while those more attuned to hands-on activities can learn how to decorate cakes or make pizzas.

Youngsters aboard either of Disney Cruise Line's two ships learn how to create animation cells (used in movie cartoons) or how to become a Mousketeer, while kids on Norwegian's ships can go on a private tour of the bridge or participate in wacky cooking classes.

Cruise ships also are allotting more of their space to children. Royal Caribbean's Navigator of the Seas, for instance, devotes a whopping 22,000 square feet to children's facilities -- more than a third more than on previous ships of the same Voyager class and more, it says, than on any other cruise line. Carnival dramatically increased the size of its children's section on its newest ship, the Carnival Conquest, and for the first time dedicated an exclusive recreation area for teenagers.

Norwegian Cruise Line's Dawn devotes much more space to children than the line's earlier ships, and even has a special children's area in its Lido restaurant complete with kid-size serving counter, tables and chairs. And Holland America's Zuiderdam, which entered service in December, gives teenagers half again as much space as exists on its other ships.

It's important to note, however, that facilities for children vary widely from line to line, from ship to ship, and from sailing sea to sailing sea. Older ships devote less space to children and may offer only minimal programs. Boutique cruise lines that attract an upscale clientele usually have few children on board, and fewer facilities for them.

Choosing the Right Ship
You won't find many children on exotic cruises such as circumnavigations of South America or voyages through the South Pacific; the Caribbean and Alaska are the two most popular for children. Bear in mind, too, that activities vary according to where the ship is sailing -- a pool party for teenagers goes over big in the Caribbean, but won't take place in Alaskan waters.

So how do you keep a cruising child -- and particularly teenagers -- happy?

''The secret,'' says Sharon Dodd, editor of Cruise Critic, an independent online cruise publication, ``is to select the right ship.''

Dodd says that's as easy as A-B-C. ``A as in Activities -- ships that feature age-specific activities are best. B as in Big -- Megaships, because of their great size, can have more facilities. C as in Clubs -- Ships that have private clubs for the exclusive use of teenagers are generally best . . . [because] their ideas of fun are very different from what their younger siblings enjoy.''

Dodd also advises sailing in summer and school holidays because more other children will be on board to make friends with. Another rule of thumb: New ships have far more facilities and programs for children than older ones.

While there's something for every child on most ships, the lines have put a lot of effort lately into pumping up entertainment for teenagers.

Both Carnival and Royal Caribbean now have divided their teen guests into two age groupings (12-14 and 15-17), a move that both older and younger teens seem to appreciate, as neither age group felt comfortable with the old mix (13-17). Norwegian puts all youth age 13-17 in their teen group.

Carnival's Carnival Conquest went further, creating a large, exclusive space for teenagers several decks removed from its Children's World area for younger kids. It's also the first Carnival ship with a ''mocktail'' lounge that serve smoothies, specialty coffees, other nonalcoholic beverages to teens.

Royal Caribbean's Navigator of the Seas set up three distinct areas that serve teens exclusively. Fuel is the name of the teen disco and bar that serves nonalcoholic drinks. Teens can hang out in The Living Room, watching television or movies, listening to music or surfing the net. In the third area, the open-air Back Deck, they can take lunch on certain days and dance under the stars at night. And don't think the younger teens can sneak into the older teens' activities or vice versa -- teen bouncers monitor the entries.

NCL's Dawn, has two large spaces for children. The Teen Club features a disco with a karaoke system, DJ booth and video wall, plus a cinema and the Video Zone -- a arcade with 25 video games. The T-Rex Childcare Center, for younger kids, includes a jungle gym, playroom, movie theater, arts and crafts area, sleeping zone, and Clicks, a computer learning center.

Teens aboard the two Disney ships, Disney Magic and Disney Wonder, hang out in a teen-exclusive room called Common Grounds, which is designed in the style of a New York coffee house and has a coffee bar, juke box, big-screen TV and Internet café. Among teen activities are a dance party in the ESPN Skybox and a daylong scavenger-hunt-like game called Gotcha, where teens roam the ship for clues.

But younger kids aren't neglected on these or any other cruise ship. Depending on their ages, they can soon be immersed in games, arts and crafts, magic shows, storytelling, beadwork, pajama parties and many other activities. And most children's centers on the new ships have computers, which are popular with a spread of age groups.

Freedom for Parents
All this effort to please youngsters frees parents to enjoy more adult activities on board -- another reason why more families are choosing to take cruising vacations. Royal Caribbean, for one, takes children to lunch or dinner three times a week on a seven-day cruise. That's a win-win situation for both kids and parents -- the kids get to eat kid food such as spaghetti or hamburgers with their friends while their parents take a blessedly unharried meal with other adults.

Similarly, youth counselors on the Carnival Conquest host special ''children's only'' meals poolside with a different cuisine featured each night, and on Disney ships children have a choice of eating with counselors or with their parents.

Babysitting is available, too, on board all ships for times when the children's centers are closed. In-cabin babysitting usually runs around $8 per hour per child, but not every cruise line offers this service. Some lines offer group babysitting (in the children's center) in the evening for $5 per hour per child and some provide babysitting on board while parents take shore excursions. Many ships issue walkie-talkies or pagers to parents so they can keep in touch with their kids and their baby sitters.

In order to participate in the onboard programs, most cruise lines require children to be at least three years of age and potty-trained. NCL, however, takes toddlers as young as 2 and not potty-trained, but parents will be called to change diapers.

Aside from babysitting and charges for some products used by in arts and crafts, children's programs are free. Most lines offer a cruise-long pass good for unlimited sodas; costs vary from ship to ship.