Alex Mustard / A diver explores Silfra Canyon, a deep fault filled with fresh water in the rift valley between the Eurasian and American tectonic plates at Thingvellir National Park, Iceland. May 2011. In this phot...

Jeff Foott / Marching Men formation, Arches National Park, Utah

Jeff Foott / Marching Men formation, Arches National Park, Utah

Jeff Foott / Marching Men sandstone formation, Arches National Park, Utah

Guy Edwardes / Sunrise through stone at Men-An-Tol, Morvah, Cornwall, England, UK. September 2016.

Ingo Arndt / Aerial view of crowd of people at the Rheinkultur Festival, Bochum, Germany.

Luke Massey / Black kites (Milvus migrans) flying above man as he throws food skyward from a rooftop. Old Delhi, India. February 2016. Finalist in the Urban category of the Wildlife Photographer of the Year Awards...

Cyril Ruoso / Inmates of the Cedar Creek Corrections Center raising endangered Oregon spotted frog (Rana pretiosa) Prisoners in this facility are raising endangered frogs for release in the wild, as part of the Sus...

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

Tony Wu / Swimmer stroking 'Scar', a male Sperm whale (Physeter macrocephalus) who often seems to seek out and enjoy contact with people. Caribbean, January 2010. Model released.

Jabruson / African elephant (Loxodonta africana) ivory in piles, ready to be burnt by the Kenya Wildlife Service (KWS). The burn included 105 tons of elephant ivory worth over $150 million Nairobi National Park...

Kristel Richard / Two cowboys mounted on a Pantaneiro stallion, round up a band of wild Pantaneiro horses, Pantanal, Mato Grosso do Sul, Brazil. August 2015.