National Geographic has created “Air, Land & Sea: the 50 greatest wildlife photographs” exhibition. Here: CT4 Crocodile cave on the Salamat river. Set up with Nathan Williamson last chip rain came while we were with the nomads. (Photo by Michael Nichols/National Geographic)

The town hall with the Mangia tower is seen in Siena, central Italy, January 29, 2016. (Photo by Max Rossi/Reuters)

Savita, a street performer, helps her dog to balance on empty tin containers as they perform at a roadside in Ahmedabad September 7, 2014. (Photo by Amit Dave/Reuters)

A man walks past an advertisement sign promoting a bank in Seoul in this September 3, 2009 file photo. South Korea is expected to release GDP dara this week. (Photo by Lee Jae-Won/Reuters)

A man poses with a hyena along a street in Lagos, Nigeria November 4, 2008. (Photo by Akintunde Akinleye/Reuters)

A Manipuri woman sells smoked and dry fish in Ima market - the world's largest all women market – in Imphal city, Manipur state, 06 January 2016. The 150-year-old Ima Keithel or “Mothers's market” complex, which is run exclusively by women and was damaged in the 04 January 2016 earthquake, is returning back to normal. Nine deaths have been reported from in and around Imphal due to falling debris. Imphal has a population of some 270,000 and people were jolted from their sleep and ran out of their homes in panic when the earth shook 04 January, reports say. (Photo by EPA/Stringer)

Young people jump over a bonfire as they take part in the Ivan Kupala Night celebration, a traditional Slavic holiday, outside the small town of Turov, some 270 km south of Minsk, on July 6, 2016. People celebrate Kupala Night with bonfires that last throughout the night with some leaping over the flames as it is believed that the act of jumping over the bonfire cleanses people of illness and bad luck. (Photo by Sergei Gapon/AFP Photo)

In this photo submitted by the Washington Post tilted “The Moment Time Stopped”, survivors piled bodies of the dead outside for weeks after earthquake on January 14, 2010 in Port-au-Prince, Haiti. The 7.0 magnitude earthquake struck in 2010, and the Haitian government has said more than 300,000 people were killed. The exact toll is unknown because there was no systematic effort to count bodies among the chaos and destruction. (Photo by Carol Guzy/AP Photo/The Washington Post)