The Umm al Samim () (also known as the Umm as Samim) is a

quicksand Quicksand is a colloid consisting of fine granular material (such as sand, silt or clay) and water. It forms in saturated loose sand when the sand is suddenly agitated. When water in the sand cannot escape, it creates a liquefied soil that los ...

area on the eastern edge of the Rub al'khali desert largely within

Oman Oman ( ; ar, عُمَان ' ), officially the Sultanate of Oman ( ar, سلْطنةُ عُمان ), is an Arabian country located in southwestern Asia. It is situated on the southeastern coast of the Arabian Peninsula, and spans the mouth of ...

's borders. The waters, such as they are, drain into this brackish low-lying

closed basin An endorheic basin (; also spelled endoreic basin or endorreic basin) is a drainage basin that normally retains water and allows no outflow to other external bodies of water, such as rivers or oceans, but drainage converges instead into lakes ...

area off the Omani mountains and the

wadi Wadi ( ar, وَادِي, wādī), alternatively ''wād'' ( ar, وَاد), North African Arabic Oued, is the Arabic term traditionally referring to a valley. In some instances, it may refer to a wet ( ephemeral) riverbed that contains water on ...

s of the Rub al'khali. The Al Samim (known locally as the 'Mother of Poisons' or the 'Mother of Worries') is a

salt marsh A salt marsh or saltmarsh, also known as a coastal salt marsh or a tidal marsh, is a coastal ecosystem in the upper coastal intertidal zone between land and open saltwater or brackish water that is regularly flooded by the tides. It is domin ...

with a solid-looking crust, but can be very treacherous when broken through. There is little vegetation. Sir

Wilfred Thesiger Sir Wilfred Patrick Thesiger (3 June 1910 – 24 August 2003), also known as Mubarak bin Landan ( ar, مُبَارَك بِن لَنْدَن, ''the blessed one of London'') was a British military officer, explorer, and writer. Thesiger's trav ...

was the first European to see the area in the late 1940s after his travels from

Salalah Salalah ( ar, صَلَالَة, Ṣalālah) is the capital and largest city of the southern Omani governorate of Dhofar. Its population in 2009 was about 197,169. Salalah is the third-largest city in the Sultanate of Oman, and the largest cit ...

in Oman.

References

Deserts of Oman Landforms of Oman Endorheic basins of Asia Salt marshes {{Oman-geo-stub