As cruise lines continue to refine their offerings to meet 21st-century lifestyle changes, vacations at sea are attracting a new generation of passengers - the GenXers.

As one savvy travel agent put it, "Younger travelers don't want their grandparents' experience. We can steer them away from that. They want more adventure in their lives."

Rob Clabbers, owner of a Cruise Holidays agency in Chicago, said he was booking a young couple on a January cruise to Antarctica. "They're both in their early 30s, well-traveled - they'd already done the Arctic - and wanted a cruise to Antarctica. They'd done their research online and were ready to make a deposit."

A cruise to Antarctica is not a cheap ticket, and the couple was not all that affluent. "It all depends on what you want to spend your money on," the agent said.

Clabbers, whose agency handles about 500 to 600 clients a year, said he'd booked a Caribbean wedding cruise for a couple in the 25-to-30 age range who thought it would be a lot more fun than renting a hall or a ballroom.

While the GenX market is growing, the average age of cruisers is 50, according to the Cruise Lines International Association, the marketing arm for 21 cruise lines.

Antarctica and wedding cruises aside, the hot destinations for this summer are the eastern Mediterranean - cruises that combine Greek islands with Istanbul and the Turkish coast - the western Mediterranean, with stops in Italy and Spain, and the Baltic, whose ports include St. Petersburg, Russia, and Stockholm, Clabbers said.

His clients also are interested in Croatia's Dalmatian Coast, especially the walled city of Dubrovnik.

Domestically, younger cruisers are going to Alaska, where they can indulge in more adventuresome shore excursions - helicopter-hiking, dog sledding, kayaking and even snorkeling, he said.

For autumn, his clients are choosing the Caribbean, shorter Panama Canal cruises (those that go through Gatun Locks into Gatun Lake, turn around and head back to the Caribbean), and New England and eastern Canada.

Nancy Kelly, president of Kelly Cruises in Oak Brook, Ill., echoed Clabber's view on European cruises this summer.

"Europe is bigger than ever. There's a lot of pent-up demand for anything from seven- to 10-, 11-, 12-day itineraries," she said.

The Baltic is her hottest destination, especially St. Petersburg, where passengers can spend two or three days in port. Turkey and Greek isles are popular, as are Italy and Spain.

"Alaska continues to be amazing," Kelly, said.

For autumn sailings, Kelly noted that the Caribbean is soft until late October and early November, after the hurricane season. Many ships that cruise the Caribbean are staying in Europe longer, not returning to the Caribbean until November or December.

CLIA has projected that 12.6 million people will take cruises this year, a 4.1 percent increase over last year, and predicts a banner year for the European market.

Here's an update on some other developments in the cruise industry that will keep passengers happy:

"Exotic" ports, hot and not so hot. If there's one really hot port for the adventurous cruiser, it's Dubai, Kelly said. "People want to see what the place is all about. It certainly is a place for an especially arranged shore excursion." Only Costa, Crystal, Seabourn and Silversea lines call there. In the "not hot" category are Beirut, torn by last summer's Lebanese-Israeli conflict, and ports in Libya, since the country barred entry to Americans.

Departure points. New Orleans, still recovering from Hurricane Katrina, has seen the return of ships from Carnival, Norwegian and Royal Caribbean lines, each with a schedule of departures to the western Caribbean. And San Diego has become a popular departure point for Baja California and other Mexico cruises.

Staying in touch. Passengers at sea can remain tethered to home through their cell phones, laptops, BlackBerries, and shipboard Internet cafes, as cruise lines supply more access. Cell-phone costs range from $1.99 to $4.99 a minute based on international roaming charges, but you must have a cell phone that works outside the United States. Ship-to-shore satellite phone calls, which can be made via stateroom phones, can run from $5 to $25 a minute. Many ships have installed Wi-Fi, largely in public areas, for Internet access.

Dining. Aboard any ship, you can still stuff your face from today to tomorrow. But cruise lines are serving healthier meals and giving passengers more dining options than first and second seatings in big dining rooms. Carnival Cruises led the industry when it began eliminating artery-clogging trans fats from its menus in 2005. Crystal Cruises recently stopped using trans fats. Other cruise lines are following suit. Celebrity chefs Georges Blanc, Michel Roux, Ettore Bocchia, Piero Selvaggio and Todd English are among the culinary experts who put their touches on cruise-line cuisine. Passengers can dine in niche restaurants, but at a price - from $10 to $35 a person.

Shore excursions. You can still board a bus and listen to a tour guide drone on, but passengers looking for excitement can go white-water rafting, rappelling, zip-lining, kayaking, fishing, rock climbing, heli-hiking - you name it. And there are alternatives to cruise-line shore excursions. Through your travel agents, you can book "one-day over-the-top excursions" that can make all the difference in the world to your trip, Kelly said. These outings, available in virtually every port, can give you an in-depth experience, whether it's spending a day viewing art with an expert at the Hermitage in St. Petersburg or a day with a naturalist in Alaska's Denali National Park.

Entertainment. From Las Vegas-style productions to doo-wop music to karaoke clubs, passengers can choose from a variety of offerings. Depending on the line, options include ballet, opera, celebrity entertainers, Disney characters, and Second City performers.

Expert lecturers. You probably won't find Al Gore lecturing on global warming, but cruise lines are keenly aware that passengers want to learn more than napkin-folding. Today's enrichment programs include Shakespearean acting taught by alumni of London's Royal Academy of Dramatic Art; language classes by Berlitz; and lectures by guest authors such as Richard Reeves, prominent journalists such as Walter Cronkite, geographers, naturalists, and wellness experts.