Geo-thermal power plant, Svartsengi, Iceland

Karst Cave at Xinwen Stone Sea Global Geo Park, Sichuan Province, China, Asia

Coastal clifftop landscape view westwards at Ta' Cenc cliffs, island of Gozo, Malta, Mediterranean, Europe

Karst Cave at Xinwen Stone Sea Global Geo Park, Sichuan Province, China, Asia

Monemvasia island historic city stone wall, Monemvasia, Laconia, Greece

Archaeological site of former Inca site at Pinkulluna, Ollantaytambo, Ollantaytambo District, Sacred Valley, Urubamba Province, Cusco (Cuzco) Region, Peru, South America

Guests from the Lindblad Expedition ship National Geographic Explorer lay in the relatively warm waters of the caldera at Deception Island, South Shetland Islands, Antarctica

Guests from the Lindblad Expedition ship National Geographic Explorer lay in the relatively warm waters of the caldera at Deception Island, South Shetland Islands, Antarctica

Guests from the Lindblad Expedition ship National Geographic Explorer lay in the relatively warm waters of the caldera at Deception Island, South Shetland Islands, Antarctica

Three caribou (Rangifer tarandus) walk by oil storage tanks near Prudhoe Bay and the Point Lonely Short Range Radar Site, where the Central Arctic herd migrates north each summer, Alaska, United States of America