Cruising the seas on a giant cruiseship is coming back and popularity is increasing tremendously - however besides wine & dine and sunshine - what else can you do in a hotel on the water?

New (and some older) vessels offer everything from onboard spas to wine cellars to surfing pools, see below a small selection.

RCCL Freedom

Modern cruise ships bear little resemblance to the sailing vessels of old. These floating resorts are jam-packed with luxurious amenities and engaging activities—not to mention first-rate food and wine. If you haven't experienced a cruise ship in a few years, you'll be wowed by today's onboard offerings.

One of the most amazing innovations of recent years has been Royal Caribbean's FlowRider. This special wave pool lets guests surf and bodyboard on the ship.

It's found on the Freedom of the Seas and Liberty of the Seas, and the best part is it's free to guests. (Photo: Royal Caribbean)

RCCL Voyager

For adventurous types, Royal Caribbean's Freedom- and Voyager-class ships and Norwegian's Norwegian Pearl feature onboard rock-climbing walls. Guests can choose easy or difficult routes, so no experience is necessary.

The ship's staff provide equipment, belay the climbers, and shout encouragement. As the rock walls are located on the top decks of the ships, this activity is not for anyone with a fear of heights. (Photo: Royal Caribbean)

Carnival Liberty

Many cruise ships have indoor movie theaters, but Princess and Carnival have placed giant LED screens on their pool decks. Cruisers can lay out on a deck chair, margarita in hand, and watch rock concerts, sports events, and recently released movies.

With Princess' Movie Under the Stars program, guests receive blankets and popcorn as they snuggle together to catch a flick. (Photo: Carnival)

Celebrity's AquaSpa

A luxurious vacation isn't complete without a trip to the spa. Spas and fitness centers are now de rigueur on cruise lines, and guests can choose from hot stone massages, aromatherapy treatments, or an old-school shave.

Onboard fitness centers are also state-of-the-art facilities. Besides the usual cardio machines and free weights, cruise lines offer yoga, Pilates, and even boxing classes. (Photo: Celebrity Cruises)

Bowling on NCL

Indoor activities are as plentiful as outdoor ones. Norwegian made a big splash with the first bowling alley at sea on the Norwegian Pearl. The ship's rocking doesn't affect the bowling balls much, but you can blame your gutterballs on it anyway.

Other incredible activities include ice skating on Royal Caribbean's indoor rinks and simulated race-car driving on the Costa Concordia. (Photo: Norwegian Cruise Line)

Holland America Line

Popular onboard learning programs feature events from expert lectures to computer classes and ballroom dancing lessons. Holland America has installed Culinary Arts Centers on its ships; guests can learn cooking techniques from famous chefs in theater-style kitchens.

Crystal keeps Yamaha keyboards onboard for cruisers who'd like to learn to play piano. Other luxury lines host lectures and discussions with famous names in film, journalism, sports, and politics, such as John Cleese and Walter Cronkite. (Photo: Holland America Line)

Teppanyaki Grill

If all this activity has got you hungry, today's cruise lines offer multiple restaurants and 24-hour dining. Norwegian's freestyle dining system lets cruisers choose when and where to eat. Onboard restaurants include a steakhouse, sushi bar, Italian family-style eatery, and the popular Teppanyaki, where chefs entertain guests by cooking Asian meals at the table.

Other mainstream lines feature onboard Johnny Rockets and Ben & Jerry's, while luxury ships tout alternative restaurants starring Le Cordon Bleu graduates and award-winning chefs. (Photo: Norwegian Cruise Line)

Crystal Cruises

Fine wines, Champagnes, and cigars highlight an evening onboard. On luxury lines Regent Seven Seas, Seabourn, and Silversea, most of your favorite vintages are complimentary.

Connoisseurs can choose to sail on a number of wine-themed cruises—even mainstream line Carnival has a voyage dedicated to the intoxicating grape.

If you're a beginner, attend an onboard wine tasting or make friends with your dining room's sommelier. (Photo: Crystal Cruises)

Snow White on stage

Not all cruise-line entertainment involves scantily clad women draped with feather boas. Disney Cruise Line features its famous characters and storylines in Broadway-style productions, and Royal Caribbean stages its own version of Ice Capades and circus parades.

Princess offers smaller acts (jugglers, a capella groups, and classical trios) in its grand atriums, and all ships offer musical acts and dancing in their lounges and nightclubs. (Photo: Disney Cruise Line)

NCL suite

When it's time to be tucked into bed, cruisers will find that they've never been so comfortable on a ship before. Big spenders can enjoy fabulous suites with their own hot tubs and sundecks, living and dining rooms, and large, lavish bathrooms.

Even budget travelers can take advantage of upgraded mattresses, linens, and bath products.

The newest ships are offering more oceanview and balcony cabins, and all staterooms have access to one of life's greatest pleasures—complimentary room service. (Photo: Norwegian Cruise Line)

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