The Dead Sea is 304 m (997 ft) deep, the deepest hypersaline lake in the world. With 34.2% salinity (in 2011), it is also one of the world's saltiest bodies of water, this salinity makes for a harsh environment in which animals cannot flourish, hence its name. The Dead Sea is 50 kilometres (31 mi) long and 15 kilometres (9 mi) wide at its widest point. It lies in the Jordan Rift Valley and its main tributary is the Jordan River.
The Dead Sea has attracted visitors from around the Mediterranean basin for thousands of years. In the Bible, it is a place of refuge for King David. It was one of the world's first health resorts (for Herod the Great), and it has been the supplier of a wide variety of products, from asphalt for Egyptian mummification to potash for fertilizers. People also use the salt and the minerals from the Dead Sea to create cosmetics and herbal sachets.
The Dead Sea water has a density of 1,240 kg/m3, which makes swimming similar to floating.
The Dead Sea's climate offers year-round sunny skies and dry air. It has less than 50 millimetres (2 in) mean annual rainfall and a summer average temperature between 32 and 39 °C (90 and 102 °F). Winter average temperatures range between 20 and 23 °C (68 and 73 °F). The region has weakened ultraviolet radiation, particularly the UVB (erythrogenic rays). Given the heavier atmospheric pressure, the air has a slightly higher oxygen content (3.3% in summer to 4.8% in winter) as compared to oxygen density at sea level.
The Dead Sea affects temperatures nearby because of the moderating effect a large body of water has on climate. During the winter, sea temperatures tend to be higher than land temperatures, and vice versa during the summer months. This is the result of the water's mass and specific heat capacity. On average, there are 192 days above 30C (86F) annually.
The Dead Sea area has become a location for health research and potential treatment for several reasons. The mineral content of the water, the low content of pollens and other allergens in the atmosphere, the reduced ultraviolet component of solar radiation, and the higher atmospheric pressure at this great depth each have specific health effects. For example, persons experiencing reduced respiratory function from diseases such as cystic fibrosis seem to benefit from the increased atmospheric pressure.
A view of the sea from the shore
The region's climate and low elevation have made it a popular center for assessment of putative therapies:
-Climatotherapy: Treatment which exploits local climatic features such as temperature, humidity, sunshine, barometric pressure and special atmospheric constituents
-Thalassotherapy: Treatment that exploits bathing in Dead Sea water
The sea is called "dead" because its high salinity prevents macroscopic aquatic organisms, such as fish and aquatic plants, from living in it, though minuscule quantities of bacteria and microbial fungi are present.