Shane P. White / Tephra during volcanic eruption, Mount Yasur, Tanna Island, Vanuatu

Paul Souders/ Worldfoto / Red algae and salt formations, Lake Natron, Ol Doinyo Lengai, Tanzania

Vincent Grafhorst / Minden / Crater of active volcano at twilight, Erta Ale, Danakil Depression, Ethiopia

Doug Perrine / Hot lava from the 61G flow, emanating from Pu'u O'o on Kilauea Volcano, flows over sea cliffs into the ocean under the stars and moon, Kamokuna, Kalapana, Hawaii Volcanoes National Park, Puna, Hawaii...

Vincent Grafhorst / Man looking into crater at night, Mount Nyiragongo, Virunga National Park, Democratic Republic of the Congo

Vincent Grafhorst / Lava in volcanic crater, Mount Nyiragongo, Virunga National Park, Democratic Republic of the Congo

Enrique Lopez-Tapia / Travelers watching lava on Erta Ale volcano crater. Afar Region, Ethiopia, Africa. November 2014.

Christophe Courteau / Lava Lake at night in the crater of Nyiragongo Volcano, Virunga National Park, North Kivu Province, Democratic Republic of Congo. September 2015.

Christophe Courteau / Lava Lake at night in the crater of Nyiragongo Volcano, Virunga National Park, North Kivu Province, Democratic Republic of Congo. September 2015.

Christophe Courteau / Steam rising from the crater of Nyiragongo Volcano. Virunga National Park, North Kivu Province, Democratic Republic of Congo. September 2015.

D. Parer & E. Parer-Cook / Volcanic caldera, Daphne Island, Galapagos Islands, Ecuador

Sergey Gorshkov / Tolbachik Volcano erupting, Kamchatka, Russia