Korean spas offer a range of experiences that range from day spas that offer inexpensive but thorough body scrubs in a roomful of women who work in their underwear (same-sex treatments only), to elaborate sauna or waterpark facilities where you can spend the day, hang out, eat, and get treatments.
One of the most popular Korean Spas is King Spa Fitness, a 40,000 square-foot spa in Palisades Park, NJ, where you can spend the day detoxifying, relaxing with friends, and getting treatments. As soon as you enter you take your shoes off, and you're in a same sex locker room where everyone goes around nude. (No fluffy spa robes here!)
You get a pair of shorts, a t-shirt for the co-ed areas, where different saunas of varying temperatures and themes are found. The amethyst sauna, gold pyramid sauna, ice sauna, and bulhanzungmok or "hot sweat" room. (You also get a cap to protect your hair from the heat.) Each sauna is supposed to have different benefits.
Back in the women's locker room, there's a herbed steam sauna,a heated mugwort room, and a hot sweat room where you can go nude. This is also where you would get a scrub and/or a massage -- not in a room by yourself but lying alongside other customers. You probably won't be catered to with all the gentleness you expect from a typical American spa.
Not all Korean spas are alike. Some are much less elaborate, and some are even more over-the-top. Spa Castle in Flushing (Queens), New York is a huge, 100,000 square foot water park modeled after traditional Asian and European bathhouses. It has mineral pools, seven specialized saunas, including L.E.D., salt, jade and loess (a type of soil), all-weather outdoor pools with a variety of jets that help relieve tension. You can also get private spa treatments here.