Dallol

The hottest inhabited place ever recorded, and nobody lives there now

Dallol lies about 130 metres below sea level in the Danakil Depression of Ethiopia's Afar Region, near the border with Eritrea, and holds the official record for the highest average temperature of any inhabited place on Earth: an annual mean of 34.6 °C recorded between 1960 and 1966. The average high across the year is 41.2 °C, the hottest month averages 46.7 °C, and the highest reading on record is 49 °C. The settlement has been described as a ghost town, and as of 2004 some buildings still stood there, built of blocks of salt.

Salt and potash brought people here. A narrow-gauge Decauville railway built in 1917 and 1918 ran from the Eritrean port of Mersa Fatma to a terminal called Iron Point, 28 km from Dallol, and potash production reached about 51,000 metric tons before large-scale supplies from Germany, the US and the USSR stopped it after the First World War. Attempts to restart it from 1920 to 1941 failed, although an Italian company did mine 25,000 tons of sylvite between 1925 and 1929. The British dismantled the railway after the Second World War, and in the 1960s the American Parsons Company drilled about 10,000 holes at 65 locations in a series of geological surveys.

The Danakil plain is a basin of marine salts laid down when the area was joined to the Red Sea, and it sits on the Afar Triple Junction, where three tectonic plates are pulling apart. Under Mount Dallol, basaltic magma meets those salts and drives springs at 108 °C that are saturated with salt, free of oxygen, carry up to 150 grams of iron per litre and run so acid that the pH falls from 0.1 to −1.7. The pools they leave are vividly coloured. Scientists of the Laboratorio de Estudios Cristalográficos in Granada, who have worked here, call it one of the few places on Earth's surface where life is impossible or almost impossible.

Paved roads reached the area in 2015, but camel caravans still come to collect salt, and off-road vehicles are the other way in. Go with an organised group, in the cool season, and carry more water than seems sensible.