Passengers ride an overcrowded bus as they head towards their village to celebrate "Dashain", the biggest religious festival for Hindus in Nepal, as fuel crisis continues in Kathmandu, October 20, 2015. Many people who live in Nepal's capital hail from districts outside the Kathmandu Valley and return home for the festival. (Photo by Navesh Chitrakar/Reuters)

Five hundred replicas of the Stormtrooper characters from "Star Wars" are placed on the steps at the Juyongguan section of the Great Wall of China during a promotional event for "Star Wars: The Force Awakens" film, on the outskirts of Beijing, China, October 20, 2015. (Photo by Jason Lee/Reuters)

White whales and their trainers present a show for visitors at Harbin Pole Aquarium on January 7, 2014 in Harbin, China. Aquarium is one of the tourist highlights of Harbin, attract domestic and foreign tourists visit each year. (Photo by Lintao Zhang/Getty Images)

Aerial view of flower fields near the Keukenhof park, also known as the Garden of Europe, in Lisse April 9, 2014. Keukenhof, employing some 30 gardeners, is considered to be the world's largest flower garden displaying millions of flowers every year. (Photo by Yves Herman/Reuters)

A member of the pro-government “red shirt” movement attacks a Buddhist monk outside the National Anti-Corruption Commission office in Nonthaburi province, on the outskirts of Bangkok March 24, 2014. Members of the movement attacked the monk after he shouted complaints to the group blocking a road near the National Anti-Corruption Commission. (Photo by Chaiwat Subprasom/Reuters)

Finding just the right spot above the clouds at Camp 1 on Ama Dablam, Danuru Sherpa uses his iPhone to catch up with friends and family. Even at 18,500 feet (5,654 meters), climbers here can check their email and other dispatches from the world below. (Photo by Aaron Huey/National Geographic)

A traffic policewoman shows her ink-stained fingers after casting her ballot at a polling station, during early voting for the parliamentary election in the northern Iraqi province of Dohuk, April 28, 2014. Iraq will be holding its national elections on April 30. (Photo by Ari Jala/Reuters)

Inside the Afar Triangle in Ethiopia’s Danakil desert, camel caravans are used to carry salt. For centuries, the essential mineral has been mined by the Afar people, known for their ability to withstand extremes. The terrain is rugged, travelers are scarce and so are motor vehicles, where the average annual temperature is the highest in the world, and can rise to 122 degrees Fahrenheit, 50 degrees Celsius. (Photo by Ziv Koren/Polaris)