El Tatio is a geothermal field with many geysers located in the Andes Mountains of northern Chile at 4,320 metres (14,170Â ft) above mean sea level. It is the third-largest geyser field in the world and the largest in the Southern Hemisphere. Various meanings have been proposed for the name "El Tatio", including "oven" or "grandfather". The geothermal field has many geysers, hot springs, and associated sinter deposits. The water from these hot springs eventually forms the Rio Salado, a major tributary of the Rio Loa, significantly increasing the amount of arsenic in the river. The geothermal vents are sites of populations of extremophile microorganisms such as hyperthermophiles, and El Tatio has been studied as an analogue for the early Earth and possible past life on Mars.
El Tatio lies at the western foot of a series of stratovolcanoes which runs along the border between Chile and Bolivia. This series of volcanoes is part of the Central Volcanic Zone (one of several volcanic belts in the Andes), and of the Altiplano–Puna volcanic complex (APVC) – a system of large calderas and associated ignimbrites which were the sources of supereruptions between 10 million and 1 million years ago. Some of these calderas may be the source of heat for the El Tatio geothermal system. There are no recorded eruptions of the Tatio volcanoes in the historical period.