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...

Alexander Badyaev / Deer mouse (Peromyscus maniculatus) on giant puffball mushroom, watching mosquito in the moonlight. Blackfoot Valley, Western Montana, USA, July. Winner of the Mammals category, Wildlife Photographer...

Bryan and Cherry Alexander / Sundogs (parhelia / parhelai) behind a 'Christmas tree' (valve assembly) in the South Tambey Gas Field, Yamal Peninsula, Siberia, Russia. February 2014.

Bryan and Cherry Alexander / A gas drilling derrick at sunset in the South Tambey Gas Field, Yamal Peninsula, Siberia, Russia. February 2014.

Bryan and Cherry Alexander / Grisha (right) and Gosha Vanuitto, Nenets reindeer herders, at their winter camp on the tundra in the South Tambey Gas Field, Yamal Peninsula, Siberia, Russia. February 2014.

Bryan and Cherry Alexander / A 'Christmas tree' (valve assembly) in front of a gas drilling derrick in the South Tambey Gas Field, Yamal Peninsula, Siberia, Russia. February 2014.

Bryan and Cherry Alexander / Oil storage tanks near Sabetta, South Tambey Gas field, Yamal, Siberia, Russia. February 2014.

Bryan and Cherry Alexander / Chukchi girls, with their family's ancestral clan mark painted in reindeer blood on their face, a ritual during the Chukchi 'Festival of the Young Reindeer' during which young reindeer are sacrificed....

Bryan and Cherry Alexander / Emperor penguins (Aptenodytes forsteri) colony, with Snow petrel (Pagodroma nivea) flying past and dark sky. Atka Bay. Antarctica

Bryan and Cherry Alexander / Chinstrap penguins (Pygoscelis antarctica) on a blue iceberg, with Antarctic Prion (Pachyptila desolata) flying over. Antarctica

Bryan and Cherry Alexander / Icicles hanging from the edge of a small blue iceberg as the summer thaw sets in, Antarctica