Treating yourself to a spa treatment can be a relaxing indulgence on a cruise. But is it any different at sea than it is on land? Here, we walk you through what you can expect, from the onboard facilities to some money-saving tips:

1. Spas at sea look pretty much like spas on land. 
The facilities are usually attached to a fitness center and, just like on land, there are also shower areas and changing rooms, where you can slip into a comfy robe and enjoy an infused water or fresh fruit as you wait for your appointment. Come early and take some time to relax before your treatments, especially if you have had a busy day.

2. Know who is in charge.
Cruise lines often hire outside companies such as Steiner Leisure or Canyon Ranch to run their spas, and you'll see both names on a variety of cruise lines. We especially love the ones run by Canyon Ranch, and the Scandinavian spas Viking Ocean Cruises developed with Oslo-based LIV Nordic. 

3. Expect to see a wide range of treatments. 
Besides the popular Swedish massage, cruise ship spas provide a variety of offerings, from body scrubs and hot stone rubs to teeth-whitening, acupuncture, and cellulite reduction therapies. The services start at around $120 for a standard 50-minute massage and go upward from there. Just use your critical thinking skills, and do research when in doubt: the laws at sea are different from those in the United States about what promises can be made in terms of results.

4. Take charge of your treatment. 
If your aesthetician starts selling you products during your treatment, do feel empowered to ask for quiet during your service. You have the right to relax and enjoy the silence if that's what you prefer.

5. Set aside time to use the facilities. 
Don't rush off after you finish a treatment — set aside time to linger in the spa’s facilities, which often include saunas, thalassotherapy pools, hot tubs, and heated ceramic loungers on large and luxury ships. Just ask in advance about the charges: Some cruise lines have begun charging extra, even for passengers who have booked treatments. Not booking a massage or facial? You can usually buy a day- or cruise-long access pass.

6. Ask about co-ed facilities.
If you are coming with your significant other, and want to spend time in thermal areas together, be sure to ask what facilities are co-ed and which ones are divided by gender. Many cruise ships have their saunas, for example, in the men's and women's changing rooms rather than in a shared space.

7. Look for ways to save money. 
For a discount, book your appointments for when your ship is in port — when most folks are off exploring on shore and the spa is near-empty. You can go often first thing in the morning or toward the end of the day, and (depending on the port) still get some sightseeing in. Also, many ships reduce prices when you purchase a package of treatments.