Danakil Depression, Ethiopia
Photograph by Carsten Peter/National Geographic
Disks of travertine, a calcium-rich deposit, ring a hot spring in Ethiopia's Danakil Depression. Afar tribeswomen extract water from this forbidding landscape by building small stone towers over the geothermal vents. The steam condenses, and the water runs into a reservoir. When it cools, the women pour it into their goatskin bags.