While some people cruise for the ports, onboard shows and other ship attractions, others love the sense of relaxation you feel when you're out at sea. For serenity seekers, a thermal suite -- an area of the spa with special whirlpools, hot tubs, showers and saunas -- just can't be beat.
For the uninitiated, the services available in a thermal suite can be confusing; with names like laconium and caldarium, you might feel like you've stumbled back into Roman times. Not to worry: The treatments themselves are simpler than their names. Often, you'll find a steam room, which will be humid; a sauna, offering dry heat; a cold room, where you cool off after those hot experiences; a vitality pool that has oxygen-intensified water; and aromatherapy showers, where you're engulfed in soothing scented water and mist.
Access to cruise ship thermal suites is not free (generally speaking), and availability is limited to ensure the spaces don't get crowded and those who pay for a daily or weekly pass can truly relax. These passes, sold through the spa or guest services, often sell out; if you're interested in the thermal spa suite, make your purchase soon after you board.
Here are our picks for the best thermal spa suites you can book on a cruise.
Photo: Cruise Critic
With heated ceramic tile loungers, several shower options, a cold room and an aromatic sauna as well as a regular sauna, Celebrity's Persian Garden provides a relaxing getaway for the line's sophisticated spa-goers. Access to the retreat is free for passengers booked in Aqua-class cabins; others can buy a weekly or daily pass.
Tip: While Celebrity has a Persian Garden on its Millennium-class ships, the ones on the Solstice-class ships are vastly superior, due to their location at the front of the ship, which provides panoramic views as you relax.
Photo: Cruise Critic
Aqua Therapy Centre
Queen Mary 2
As you might expect on Cunard's flagship ocean liner, the thermal suite on Queen Mary 2 is expansive enough to keep participants occupied on lengthy transatlantic crossings. Run by Canyon Ranch, the suite includes a good-sized pool, a whirlpool, reflexology basin to relax your feet and sensory showers with different pulse options. Sauna-lovers will be in heaven, with a choice of a traditional Finnish sauna, an aromatic steam room and an herbal sauna before cooling down with the ice fountain.
Tip: While access to the Aqua Therapy Centre requires the purchase of a voyage-long SpaClub Passport, passengers who book a spa treatment also can access the thermal suite free of charge. Just make sure you leave enough time before or after your session to indulge.
Photo: Iglu Cruise/Flickr.com
Norwegian Cruise Line
Norwegian Cruise Line has fairly elaborate thermal suites on Norwegian Epic, Norwegian Escape and Breakaway-class ships, Norwegian Getaway and Norwegian Breakaway. Within the space, you'll find trendy "salt rooms" encased with layers of salt crystals, designed to improve respiratory problems and skin ailments. Other elements of the Thermal Suite include a steam room, a dry sauna, a vitality pool, heated tile loungers and hot tubs.
Tip: Word on the Thermal Suites is out, and the limited passes that are good for a weeklong sailing sell out quickly. If you're interested, make a stop at guest services a priority on embarkation day. Day passes are available at a discounted rate to those who purchase a spa treatment.
Photo: Cruise Critic
Viking Ocean Cruises
While not thermal suites per se, the spas on all Viking Ocean cruise ships qualify, as they provide a number of hot and cold therapies. There's a warm-water thalassotherapy pool, plush loungers, two therapy showers, a steam room and a Finnish sauna. The spa also has a first-at-sea snow grotto, a small glassed-in room in which ice shavings fall each day. (Don't worry, when you get cold, you can warm up on heated stone loungers outside the snow grotto or retreat back into the steam room.) The best part: It's free to all passengers -- no special cabin class or purchase of a spa treatment is required.
Tip: A couple of things to know about the snow grotto: First, it can get slippery, so you'll want to wear soled slippers. (We also recommend going early in the morning, when the snow is fresh.) Second, the snow grotto needs to be defrosted and cleaned once per cruise. So try to leave some wiggle room in your schedule, if your heart is set on trying it.
Photo: Viking Ocean Cruises
Princess' Royal Class
Princess has thermal suites on its Coral and Grand classes (with the exception of Golden Princess and Grand Princess), but its Royal-class vessels, Royal Princess and Regal Princess, take the concept up a couple notches. The Enclave boasts a hydrotherapy pool and accompanying rain shower, heated tile loungers and water beds, sensory showers with mood lighting and therapeutic aromas. Three named rooms offer a variety of heat-based experiences: the Hammam, a Turkish-style bath, featuring a marble slab for mud or salt treatments; the Caldarium, a ceramic chamber infused with herbal aromas; and the Laconium, a dry sauna.
Tip: Access is granted by a weekly pass that sells out quickly. It might not be in the spirit of relaxation to rush to claim a spa pass, but if you don't get one shortly after embarkation, you'll be out of luck.
Photo: Cruise Critic
Holland America's Koningsdam
Snag a day pass for Koningsdam's thermal suite, and you might find yourself wishing you'd purchased one for the entire week. The facility is not only one of the most gorgeous at sea, but it also has a wide variety of thermal suite alcoves that allow you to try something new every day. Spa-goers will instantly gravitate toward the spa's large thalassotherapy pool, complete with body massagers, a rain shower and sparkling overhead lights that give the illusion of a starry night sky. Other standout features include an aromatherapy room, "lazy" shower (you lie down on a ceramic bed instead of standing up), cold water bucket shower, an infrared sauna and sweeping views -- which can be enjoyed from the relaxation room, ceramic lounge, sauna and steam room.
Tip: Purchase your spa pass on embarkation day. Many times, the line offers first-day discounts (such as $100 off a weeklong couple's pass). This also ensures you claim your spot, as passes tend to sell out quickly.
Photo: Holland America Line