During the Pleistocene it was sometimes a lake, but today only parts of the salt pan are covered by perennial water bodies; its major tributary is the Río de los Patos.

Salar del Hombre Muerto is a 600-kilometre (370 mi)[4] salt pan with irregular margins[5] resembling a square.

Between the two lies a central island named Farallon Catal[6] with an area of 72 square kilometres (28 sq mi) that separates Hombre Muerto into two halves,[7] an eastern one and a western one;[8] the eastern part (also known as Salar de Vida[8]) is covered by debris, while the western part is covered by evaporites[9] with a polygonal surface appearance.

[10] Two other islands are the Tetas de la Pachamama in the eastern and Cerro Oscuro in the southern sector of the Salar.

[11] Close to Salar del Hombre Muerto lie ten potential impact craters with diameters of 90–250 metres (300–820 ft) that may have formed during the last 500,000 years[12] and certainly very recently, although they could also be collapse structures in the underlying alluvial fan.

[13] The watershed of Salar del Hombre Muerto has an area of 4,000 square kilometres (1,500 sq mi),[4] half of which is drained by the 150 kilometres (93 mi) long Rio de Los Patos; this river enters into the salar from the northeast but originates on Galán and the Eastern Cordillera south of Hombre Muerto.

The Los Patos river has a discharge of 0.8–2 cubic metres per second (28–71 cu ft/s) and supplies a perennial lake, named Catal Lagoon, and during the rainy season large parts of the salt pan can flood.

[28] The climate is arid;[29] the 60–80 millimetres per year (2.4–3.1 in/year)[5] precipitation originates mainly in the Amazon and comes to the salar during summer, but winter snowfall also occurs.

[37] The name "Salar del Hombre Muerto" means "Salt Pan of the Dead Man"[38] and may be a reference to the presence of mummies in the area.

[51] The lithium-rich brines may have formed through the leaching of pyroclastic rocks;[52] their total amount at Salar del Hombre Muerto is estimated to be 800,000 tons.

[53] Another mining project at Salar del Hombre Muerto is called "Sal de Vida";[10] it is run by Galaxy Resources and was underway as of 2021.