On the North-Eastern coast of the gulf of Geras, at a distance of 8.5 kilometers from the city of Mytilini, the hot springs of Therma gulf of Geras appear.
The springs emerge at the base of the steep slope created by the fault system of the Gera Bay, in Neogene sediments that include layers of clay and sandstone. At the point of the hot springs, the NW-SE faults, which delimit the eastern side of the gulf, are intersected by the younger faults of the Larsos rift zone with NE-SW direction. The water moves through the tectonic surfaces, descends to a depth of 2.5 kilometers, is heated, and then rises and gushes out at the Therma site.
The water temperature is 39.7°C and the source is defined as sodium chloride. Water contains ammonium chloride, sodium bromide, potassium nitrate, calcium chloride, magnesium chloride, etc.
The old facilities date back to the time of the Turkish occupation and are perfectly preserved to this day. Today, a modern hydrotherapy center operates in Therma and provides high quality services.