The Dead Sea is a hypersaline lake with a salinity level of 33.7% that borders Jordan, Israel and the West Bank and covers an area of ~600 km2 (230 sq mi). Hypersaline means that it has an unusually high concentration of salts (sodium chloride and others) and has a higher salinity than the ocean (3.5% salinity). While the Dead Sea is not the saltiest lake in the world – that honour belongs to the Don Juan Pond in Antarctica – it is the deepest, with a maximum depth of 307 m (997 ft) below the surface. The lake is also Earth’s lowest point on land with the lake’s surface at an elevation of 429 m (1,407 ft) below sea level.
The name “Dead Sea” refers to the fact that most life forms (with the exception of some bacteria and microscopic algae) cannot survive in its waters. However, the lake has drawn interest from medical researchers who are using the unique chemical and physical properties of its mud and water to treat number of health conditions including psoriasis (a chronic skin condition) and osteoarthritis of the knees.
Sadly, the Dead Sea may be dying. Due to water diversion from the Jordan River which normally flows in from the north (visible as a thin line at the top of the image), the level of the lake (as well as the underlying groundwater) has dropped significantly. The image I’ve included shows the drop in water level since 1972. At the southern end of the lake you can see the mineral evaporation ponds from which carnalite (potassium magnesium chloride) is harvested.
As a result, sinkholes (up to 1 per day) have begun forming in the area as briny groundwater is flushed out by freshwater. The freshwater then dissolves away the rock, forming caves. that grow larger and collapse, causing sinkholes and an elaborate underground drainage system. This link describes the causes and consequences of the Dead Sea decline. Via Facebook.