In recent times, Kythnos got its second name, "Thermia", from the hot springs, which are located in the picturesque bay of Loutra, on the northeastern side of the island.
The only thermal baths in the Cyclades are located in Loutra.
Loutra is famous for its thermal springs, known since antiquity as finds have been found in the area.
Most likely they existed in antiquity, but were used only in Roman or Byzantine times. Archaeologists come to this conclusion due to the existence of various findings: a brick bath, in which water flowed a ditch that came from the source of Ag. Anargyron, five tombs around the springs as well as a small glass vase.
All these evidences testify that the use of the baths took place at a time when Christianity was not yet widespread in Kythnos. The ruins of the ancient baths were visible until 1782. Then a local architect, Konstantinos Zanakis, under the supervision of Nikolaos Mavrogenis, interpreter of the Turkish fleet, and at the expense of the community of Messariotes, built a vaulted tank in the bath instead of a bath. . Anargyron.
There is a wall inscription since then which reads: "Building at the expense and expense of the most glorious and esteemed lord dragoon of the large fleet, Mr. Nikolaos Mavrogenous. ΑΨΠΒ July 28 ΚΗ ». The precious "evil water" was neglected by the Kythnians. It was believed that down there in these springs the devils of hell worked and that Kokkina, where the hot springs were located, was the abode of the fairies which many of the locals claimed to have seen dancing and singing.
The locals used the springs for washing and pressing, as they say, mainly woolen handmade rugs and carpets.
In recent years, their usefulness in curing mainly gynecological diseases but also for the treatment of rheumatism and arthritis was first discovered by German doctors and chemists brought from Bavaria by King Otto in order for Queen Amalia to become a mother. The staff consisting of the leading doctors of the time, who, having extensive experience in hydrotherapy, which was already in great development in Central Europe, were looking for the right thermal water throughout Greece, in order to help the young queen. It is said that they considered Kythnos and its thermal water ideal for infertility.
At the Hydrotherapy Center there are even today the marble baths that were made in order for the royal couple to take a bath. The hot thermal waters reach the hydrotherapy center from the two hot springs that are almost next to each other and gush from them.
This is the spring of Agioi Anargyroi, whose waters are mainly saline with a temperature of 38 ° C and the second, the spring of Kakavos which is located 50 m from the first, contains iodine, bromide and sodium chloride and its temperature reaches 52 degrees Celsius. The hydrotherapy center is open from June to September
Many people (mainly the elderly but also people with arthritic problems, muscular and neurological problems) arrive for this reason, choosing the part of the Baths for their summer vacation.
Nowadays Loutra has a special tourist development as in addition to the spa tourism infrastructure, they are located near small beautiful beaches (Agia Irini, Schinari, Agios Sostis and Potamias) while they have an organized port with a marina for sailing boats and other yachts. Hotels, rooms to let, restaurants and ouzo are plentiful in the settlement of Loutra. There is also a car & moped rental office, diving school, bakery and super market that serve the needs of the area.