Looking down into Ubehebe crater, a Maar volcano, caused by groundwater contacting hot magma or lava, Death Valley National Park, California, United States of America, North America

Randecker Maar, former volcanic pipe, Ochsenwang, Swabian Alps, Baden-Wurttemberg, Germany, Europe

Looking down into Ubehebe crater, a Maar volcano, caused by groundwater contacting hot magma or lava, Death Valley National Park, California, United States of America, North America

Aerial view of Windsborn crater lake, rural district of Daun, Eifel, Rhineland Palatinate, Gemany, Europe

Aerial view of Windsborn crater lake, rural district of Daun, Eifel, Rhineland Palatinate, Gemany, Europe

Gemundener Maar, Volcanic Eifel, Vulkaneifel, Schalkenmehren, Rhineland-Palatinate, Germany, Europe