Cruise lines lure couples onto their ships with promises of romance for all ages. After all, what could be more lovely than watching the evening sky turn pink across a calm sea with your loved one?

Indeed, cruisers typically travel in pairs, says Cruise Lines International Association, with married couples representing 80 percent of the passengers. We can think of a few ways to kindle the fire on any itinerary -- like cozying up with a room service dinner or making a reservation at an intimate specialty restaurant. You can always spring for a side-by-side massage at the spa and try the hot tub after dark (when kids who run around during the day will be all tucked in). Or, during a port of call, why not take a horseback ride on the beach or sign up for a two-person parasailing excursion?

But for those who want to take romance to the next level yet, cruise lines also offer many romance and special event packages that feature amenities designed to create just the right mood:

Royal Caribbean International's Grand Romance package, for example, starts with cupcakes and a bottle of bubbly upon arrival. You'll also be treated to a bouquet of fresh flowers, pre-dinner canapés and post-meal petit fours in your stateroom on formal nights, and a keepsake portrait in a silver frame. Finally, you'll get two Turkish cotton bathrobes -- the coveted amenity that sets this $200 package apart from the basic $100 romance package.

With Norwegian Cruise Line, the $399 Ultimate Romance treats couples to such romantic inducements as two massages, two dinners in a specialty restaurant with wine, and two breakfasts served in bed. That's not to mention a dozen red roses, plus sparking wine and chocolate-covered strawberries delivered to the stateroom upon embarkation.

Luxury lines get in on the action, too. Seabourn created Spa Villa packages that promise guests they'll “indulge like never before.” At a per couple cost of $500, cruisers can book their own personal outdoor villas on the spa deck, luxuriating in personalized packages such as “Sanctuary for Two” and “Sweet Surrender.” Treatments are performed in the villa, then guests can choose from the line's spa menu for food and drinks as they lounge and linger.

In recent years cruise lines have also added celebration packages for couples marking a special anniversary, often involving vow renewal ceremonies. On Norwegian's ships, $599 will get romancers a Private Vow Renewal package that features amenities such as a sparkling wine and chocolate-covered strawberries in the stateroom, a renewal ceremony performed by the ship's staff, a cake for two, and a private dinner at a specialty restaurant. To commemorate the event, couples come away with a vow renewal certificate, professional portrait, and engraved frame.