Dallol

Dallol is a volcanic explosion crater (or maar) in the Danakil Depression, northeast of the Erta Ale Range in Ethiopia. It has been formed by the intrusion of basaltic magma in Miocene salt deposits and subsequent hydrothermal activity. Phreatic eruptions took place here in 1926, forming Dallol Volcano, numerous other eruption craters dot the salt flats nearby. These craters are the lowest known subaerial volcanic vents in the world, at over 45 m (150 ft) below sea level.

• http://en.wikipedia.org/wiki/Dallol