Most spas have hot tubs and sometimes dramatic water features in their locker room areas or outdoor pools, but I don't consider it true hydrotherapy. That's because the spas have to introduce sanitizing chemicals, and those can be absorbed into the body. I generally avoid these shared tubs and pools.
You can get some of the benefits of "contrast bathing" (alternating hot and cold, which stimulates the body's circulatory system) by spending time in a steam room or sauna, then jumping in a cold shower. Repeat a few times for best results.. Some saunas even have showers inside them, which makes it easier.
Different Types of Hydrotherapy Treatments
Mineral springs spas specialize in hydrotherapy, with waters that have trace elements that benefit for the body. The exact makeup of the water vares from spring to spring, and different waters are considered beneficial for different ailments. They may offers individual baths, communal pools, or both.
Not all spas offer hydrotherapy treatments. The bigger and more elaborate the spa, the more likely it is to offer some form of hydrotherapy. One of my favorites is aVichy shower, which usually follows a scrubs or wrap. You basically get a shower with five or seven heads while you're laying down.
Some body treatments involve a shower with lots of heads installed so that water comes at you from different directions, chest down. This feels pretty good, but the pressure has to be good and the heads well positioned.
Some spas have installed "rain showers" with special effects like sound, light, and even aroma. These can be fun but I think they are basically entertainment.
Scotch showers are a form of hydrotherapy where high-pressure hoses are wielded by a therapist who is basically giving you a massage at a distance with a well-placed blast of water. You stand at the end of a long tile shower, and the therapist is at the other end. These are not that common in American because it's expensive to install, not that well understood, and requires skill by the therapist. I had one once and it was amazing.
Another option is therapuetic baths with jets that circulate water, which often has additives such as dried algae to help remineralize the body. Often these baths are part of a signature treatment. These baths are less common than they used to be because spas found that most people don't want to pay to be left alone in a bath. It can be worth it if it involves hands-on underwater massage with hoses.
The Meaning of Thalassotherapy
Thalassotherapy is a form of hydrotherapy that involves the therapeutic use of the ocean waters and marine products like algae, seaweed, and alluvial mud. The name comes from the Greek words thalassa ("the sea") and therap ("treat"). True thalassotherapy spas are popular in France, but hard to find in the U.S.
The principle behind thalassotherapy is that repeated exposure to sea air and immersion in warm seawater, mud, clay, and protein-rich algae helps restore the body's natural chemical balance. Seawater and human plasma are very similar. When immersed in warm seawater the body absorbs the minerals it needs through the skin.
You can always take a warm bath at home and add epsom salts or quality marine products like the ones from Spa Technologies. Some of the benefits of warm bathing are stress relief, softening dead skin cells for easy exfoliation, and detoxification or remineralization, depending on what you add to the bath. Best thing of all? It's free to take a long, relaxing bath.