Hot springs are mineral water coming out of the ground with more than 5 ° C of the surface temperature.
These waters come from underground layers of Earth that are at a higher temperature, which are rich in various mineral components and allow their use in therapeutics as baths, inhalations, and heating. It is usually found along fracture lines as along the tectonic plates can enter groundwater are heated at a certain depth and then rise as vapor (which may condense to reach the surface forming a geyser) or hot water.
Iceland is situated on the Mid-Atlantic ridge, a source of active high-temperature areas. There is a great deal of a volcanic activity on the ridge and therefore a unique interplay of fire and water. The high-temperature areas are along belts of volcanic activity, and their steam is utilized to drive turbines and produce electricity as well as to heat up cold water.
The hot water in the Reykjavík metropolitan area comes from both low and high-temperature areas. There are about 60 boreholes in the city of Reykjavik´s low-temperature areas. Boreholes may be seen in Reykjavik on Engjateigur; the deepest borehole there is about 3km deep. However, the majority of boreholes are 1-2km deep.
The temperature of the water coming from boreholes in low-temperature areas can be up to 150°C.
There are around 170 swimming pools in Iceland, providing Icelanders with a special quality of life. The pools are a source of health and healthy exercise, outdoor recreation and pleasant socialising the year around. The majority of these pools are heated with geotermical water. Other swimming pools are heated with electricity or the energy provided by waste incineration. Some pools utilize geotermical water by letting in flow through heat exchangers, using it to heat up cold water.
Icelanders have used hot water for bathing since de Settlement Period, and the oldest and most famous pool is probably Snorralaug in Reykholt. The pool, named after Snorri Sturluson, figures in Sturlunga Saga. Snorri is though to have lived from 1178 to 1241. The first hot pool (hot pot), built according to ancient tradition, was opened in 1962 in Vesturbæjarlaug.
Today, hot pots are an important feature of icelanders´swimming pool culture.
Swimming instruction began in both Reykjatjorn in Skagafjörður and Laugardalur in Reykjavik around 1822-23. Later, swimming instruction in hot water also began on Reykjanes peninsula in Isafjardardjup. In 1925 a law was passed authorizing towns and local governments to require young people to take swimming lessons.
Today, all Icelandic children learn to swim, starting at the age of six. Swimming instruction, however, is far from the only use made of the pools.
People go there for healthy exercise, fun and relaxation; in fact, it is a true indulgence to relax under the open sky in the hot pot and chat about people and issues.