Dallol is a unique, terrestrial hydrothermal system around a cinder cone volcano in the Danakil Depression, northeast of the Erta Ale Range in Ethiopia.

[1] The term Dallol was coined by the Afar people and means dissolution or disintegration, describing a landscape of green acid ponds and geysers (pH-values less than 1) and iron oxide, sulfur and salt desert plains.

[7] Dallol lies in the evaporitic plain of the Danakil Depression at the Afar Triangle, in the prolongation of the Erta Ale basaltic volcanic range.

[8] The intrusion of basaltic magma in the marine sedimentary sequence of Danakil resulted in the formation of a salt dome structure, where the hydrothermal system is hosted.

[1] The hydrothermal springs of Dallol discharge anoxic, hyper-acidic (pH < 0), hyper-saline (almost 10 times more saline than seawater), high temperature (hotter than 108 °C or 226 °F) brines that contain more than 26 g/L of iron.

[1] Another fascinating feature of Dallol is the wide array of unusual mineral patterns such as salt-pillars, miniature geysers, water-lilies, flower-like crystals, egg-shaped crusts, and pearl-like spheres.

[19] In October 2019, a French-Spanish team of scientists published an article in Nature Ecology and Evolution[20] that concludes that while the salt plains are teeming with halophilic microorganisms, there is no life in Dallol's multi-extreme ponds due to the combination of hyperacidic and hypersaline environments, and the abundance of magnesium (which catalyzes the denaturation of biomolecules).

[citation needed] But the hostility of the depression, the unbearable heat which reigns there, and the dangers of the site (acid basins, toxic fumes), did not favour the exploration of the zones close to the crater.