We love cruising for the lavish dining options, awesome entertainment, and incredible off-shore excursions. But lately, there's a new reason for going onboard -- top-notch spas. These days, cruise ships offer immersion into stress-free living with luxuriously heated ceramic beds, relaxation pools, and one-of-a-kind massages. Here, five of the best cruise ship spas.

Princess Cruise Lines: Regal Princess
Completed in 2013, the Regal Princess is Princess Cruise Line’s newest addition to its fleet of upscale and elegant cruises. The 10,000-square-foot Lotus Spa onboard the Regal is an expansive oasis of relaxation featuring more treatment rooms than any other Princess cruise ship. A first for Princess, the ship's relaxation hideaway, The Enclave (included for suite passengers, $39 a day and full-voyage passes starting at $219), is outfitted with heated stone beds, relaxing water beds, and spa rooms with steam, sauna, and aroma sensations. Guests find solace in the Turkish-style co-ed soaking bath finished in marble. Facials at the spa start from $69 for 50 minutes, with 50-minute Swedish massages starting at $119.

Norwegian Breakaway
New York’s cosmopolitan feel continues aboard Norwegian Cruise Line’s newest ship, the Norwegian Breakaway, where the Mandara Spa is the ideal place to relax aboard the busy ship. Placed at the bow of the tall ship and about 40 percent larger than the other line’s spas, the panoramic views are stunning. Numerous heated beds provide the perfect opportunity for an afternoon nap before or after their Seven Sea Massage (50 minutes for $99), a treatment that incorporates massage techniques from around the world. The Mandara spa features a relaxation pool, hot tub, sizeable saunas, and a salt room for respiratory problems and skin ailments. The spa offers a day pass for $39 and weekly passes for $119 per person.

Royal Caribbean: Quantum of the Seas
The new Quantum of the Seas achieved countless firsts in ocean liner travel when it launched in 2014. Home-porting in Bayonne, NJ, about 30 minutes from New York City, this ship features a host of thrilling activities such as bumper cars, simulated skydiving, and an incredible observation pod that extends over the ship. The Vitality Spa on Deck 15 is an oasis of serenity aboard the active ship, complete with 22 treatment rooms. The spa’s thermal suite is smaller than expected but offers a luxurious feeling with its heated ceramic beds, steam, and dry sauna. Pro tip: There are only 30 day passes available per day ($30 a day) with a limited amount of weekly passes, so be sure to book prior to your cruise to ensure access.

Celebrity Summit
It’s all about Canyon Ranch aboard the Celebrity Summit, the world-renowned destination spa that has made its way to the seas via Celebrity Cruises. Canyon Ranch’s SpaClub encapsulates the signature treatments and feel of Canyon Ranch’s indulgent luxury alongside views of endless horizon. Facilities onboard in the spa’s Persian Garden include hot tubs, relaxation pools, comfy lounge chairs, and accessories including plush robes, slippers, and towels. Pass time in the aromatic steam room where eucalyptus oils cleanse and rejuvenate before experiencing the sensory showers with six water jets and an overhead spray. Passes to the Persian Garden are included with suites at $25 a day and $75 for six days.

Cunard Cruises: Queen Mary 2
Stately luxury and sophisticated style is the cornerstone of the Queen Mary 2’s lasting legacy of international cruising. Similar to the Celebrity Summit, Canyon Ranch has arrived on the Queen Mary 2, bringing its exclusive SpaClub and one-of-a-kind treatments aboard. Custom built for the ship, the SpaClub onboard differs from the Celebrity Summit with unique whirlpools, relaxation vistas, and a host of unique treatments. The spa is the largest afloat with 20,000-square-feet of relaxation space. The basic massage at the spa starts at $149 for 50 minutes, while you can try acupuncture for $169 for 50 minutes or their age-defying manicure comes in at $101 for 45 minutes. Access to the spa starts at $40 a day and goes up to $105 for a transatlantic crossings.