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

Ernie Janes / Abstract photo of Tower Bridge, with blurred motion red bus, London, June 2013. Digitally manipulated.

Andy Rouse,Andy Rouse / Ring tailed Lemur (Lemur catta) mother carrying baby on back. Madagascar.

Tom Gilks / Bicycle taxis with passengers carrying people, Kisumu, Kenya, February 2013.

Tom Gilks / View from the back of a Matatu mini van taxi, Kenya. February 2013.

Ingo Arndt / Travelers Palm (Ravenala madagascariensis) close-up view of fronds, Christmas Island, Indian Ocean, Australian Territory

Ingo Arndt / Travelers Palm (Ravenala madagascariensis) close-up view of fronds, Christmas Island, Indian Ocean, Australian Territory

Staffan Widstrand / Polar travelers photographing Walrus (Odobenus rosmarus) Svalbard, Norway, September.

Tim Laman / National Geographic Explorer walking along path on New Island, Falkland Islands, March 2011.

Kristel Richard / Marbach staff in traditional uniform driving four Wurttemberg stallions during the stud's 500th anniversary celebrations. Marbach National Stud, Swabian Alps, near Reutlingen, in Baden-Wurttemberg, Ge...

Steve O. Taylor (GHF) / West African refugees crossing the Sahara on their way to Europe, Niger, 2005.

Steve O. Taylor (GHF) / Peul / Fula woman travelling to new encampment on donkey, central Niger, 2004.