Despite all those scheduled shore excursions and back-to-back onboard activities, a cruise is a great opportunity to simply relax and rejuvenate. When else will you have time for a full workout followed by a 90-minute massage? These days, almost every cruise line has an onboard spa with sophisticated amenities and treatments, a well-equipped gym and a full roster of fitness classes. The newer the ship, the bigger and better the spa—and many deliver health and beauty services you can only find at sea. Here are our top choices.

CARNIVAL
Like all things Carnival, the Carnival Splendor, which launches in July, is huge. Its Cloud 9 spa (run by Steiner, the ubiquitous spa-at-sea company) covers 21,000 square feet stretched over two decks. There’s a large thalassotherapy pool (think whirlpool on steroids) under a glass dome, plus a “thermal suite” with four steam rooms at different temperatures.

Best Feature: Sixty-eight spa staterooms and suites that come with in-room fitness gear and yoga mats. Those guests have unlimited spa access, and a private elevator to get there.

CELEBRITY
Known for its upscale service, Celebrity launches the Solstice this fall. The ship’s sprawling AquaSpa will have an acupuncture room, a salon and a eucalyptus steam room called the Persian Garden. Even if you haven’t booked a treatment, you can always stop by the spa’s café for a healthy lunch of smoothies, grilled fish or salad.

Best Feature: The Rasul Treatment is child’s play for grown-ups: Couples smear each other with different colored mud, then rinse off in a rain shower.

CRYSTAL
One of the poshest ships at sea, the Crystal Symphony (with a Nobu restaurant onboard) was fully renovated in 2004. Its Crystal Spa, run by Steiner, also received a major update. It’s a modern, feng shui–oriented facility (no surprise, since the line is owned by a Japan-based company) with treatment rooms that look out to sea.

Best Feature: The Yin Yang facial, which uses botanical essential oils to soothe and balance the skin.

CUNARD
The Queen Victoria, launched with much fanfare in Southhampton last December, is scheduled to spend most of her time sailing northern and southern Europe and the Baltics. While the QM2 has a Canyon Ranch-branded spa, the QV manages her own: the 13,000-square-foot Cunard Royal Spa. You’ll find state-of-the-art hydrotherapy pools, pilates classes and a gym. The thermal suite, essentially a private infinity whirlpool surrounded by windows, is breathtaking.

Best Feature: Kerastase products—typically beloved by beauty editors everywhere—are used in the salon’s four signature conditioning treatments. You’ll disembark with hair that’s never looked healthier.

HOLLAND AMERICA
While this mid-priced line still adheres to many cruising traditions (such as steaming mugs of bouillon served on deck in chilly weather), it too is modernizing, adding cooking-demo stadiums and Internet cafés. The line recently acquired the Texas-based Greenhouse Spa for its fleet, and installed the first in the Noordam, which launched in 2006. Check out the thermal suite, with heated stone lounge chairs and a Turkish bath-style atmosphere; guests can proceed through different rooms for dry heat, steam and aromatherapy mist.

Best Feature: The enormous floor-to-ceiling windows in the treatment rooms. If you manage to stay awake, you can gaze out to sea during your session.

PRINCESS
Last May, a former Renaissance ship was relaunched as the Royal Princess, equipped with all of Princess’s signature amenities: pottery classes on deck, a steakhouse, the Italian restaurant Sabatini’s and more. The spa became the Asian-inspired Lotus Spa; while it’s not an enormous space, it is sophisticated and peaceful.

Best Feature: The lime and ginger salt exfoliation, followed by a deep-tissue massage, is the best prep for a relaxing day in the sun. 

REGENT SEVEN SEAS
The five-year-old Seven Seas Voyager is this luxury line’s largest and newest ship. It carries 700 passengers in spacious cabins with large marble bathrooms and long balconies. The onboard spa is a seaworthy outpost of the renowned Carita of Paris Spa.

Best Feature: The Renovateur, Carita’s secret process since the 1960s, exfoliates with a blend of sunflowerseed and essential oils, followed by a special technique that’s said to “sculpt” skin contours.

SEABOURN
Until the Odyssey debuts in June 2009, the Seabourn Legend (circa 1992) is the line’s youngest ship. Despite that, it feels like a grand dame hotel at sea—heavy draperies and brocade, elegant dinners with menus by Charlie Palmer. The spa is cheerful and intimate, though, with honey-colored tiles and lots of blond wood. Its salon is especially popular for formal-night hairdos. Also appreciated: mini neck-and-shoulder massages, offered free of charge to guests on the pool deck.

Best Feature: The pre-sun, 75-minute Body Glisten Granule Rub. You’re scrubbed smooth with a minty polish, then massaged.

SILVERSEA
The seven-year-old Silver Whisper is the newest ship in this elegant luxury fleet, with the most space per guest on any cruise vessel—7,400 cubic feet. Its serene Spa at Silversea, which was completed last October, focuses on anti-aging and total well-being—including a massage with volcanic basalt stones from South America, which are heated and then placed along your spine and between your toes.

Best Feature: Trainers can design a personal regimen by comparing your body age with chronological age, using body fat, cardio health and flexibility. Too much information? You can always opt for that facial instead—it is a vacation, after all.

Pillow Talk
A few words of advice before you lie down on that massage table.

Try something new.
Cruise ships often offer quirkier services than your average landbased spa. Some ships (including Celebrity’s) list ionotherapy, for example: a weight-loss technique using negative ions in mineral-infused waters and seaweed.

Be assertive.
While spa employees in the United States usually postpone the sales pitch until after the treatment, technicians on cruises often start pushing products while you’re still on the table. If it’s preventing you from enjoying yourself, say so. You can always listen once your time is up.

Book early.
Bear in mind that sea days are the most popular times to get a treatment. The fewer sea days on your itinerary, the more coveted the spots. Check to see if your line allows pre-booking; if not, reserve your treatments as soon as you board to make sure you get the times you want.

Let RCI® book your next cruise. To learn more about RCI’s cruising options, visit cruiserci.com, or call 877-RCI-BOAT (877-724-2628).