Two Bulgarian tourists pose in front of the Eiffel Tower in Paris on their last day in the capital on March 24, 2014. (Photo by Franck Fife/AFP Photo)

“Diver in Magic Kingdom”. Green Lake (Grüner See) is located Tragöss Austria. In spring snowmelt raises the lake level about 10 meters. This phenomenon, which lasts only a few weeks covering the hiking trails, meadows, trees. The result is magical to watch diving landscapes. Photo location: Grüner See at Tragöss, Austria. (Photo and caption by Marc Henauer/National Geographic Photo Contest)

Growing cities, overuse of fertilizers and factory wastewater have degraded China's water supplies to the extent that half the nation's rivers and lakes are severely polluted. China aims to spend $850 billion to improve filthy water supplies over the next decade, but even such huge outlays may do little to reverse damage caused by decades of pollution and overuse in Beijing's push for rapid economic growth. Photo: Fishermen row a boat in the algae-filled Chaohu Lake in Hefei, Anhui province, June 19, 2009. (Photo by Jianan Yu/Reuters)

Passengers take photos at a wildfire while traveling on a train in Zamora, Spain, Monday, July 18, 2022. When Francisco Seoane's train unexpectedly stopped in Spanish countryside that was being engulfed by a wildfire, he and other passengers got a fright when they looked out at flames encroaching on both sides of the track. The Spaniard told The Associated Press it was scary to see how quickly the fire spread. Video of the unscheduled – and unnerving – stop shows about a dozen passengers in Seoane's railcar appearing alarmed as they look out of the windows Monday. (Photo by Francisco Seoane Perez/AP Photo)

A young worshipper holds a lotus flower as Buddhist monks gather at Wat Arun Buddhist temple during Asaha Bucha day in Bangkok on July 20, 2024. (Photo by Chanakarn Laosarakham/AFP Photo)

People walk down the street while Hurricane Matthew approaches in Port-au-Prince, Haiti October 3, 2016. (Photo by Carlos Garcia Rawlins/Reuters)

An Indian Air Force person walks carrying a Nepalese child, wounded in Saturday's earthquake, to a waiting ambulance as the mother rushes to join after they were evacuated from a remote area at the airport in Kathmandu, Nepal, Monday, April 27, 2015. The death toll from Nepal's earthquake is expected to rise depended largely on the condition of vulnerable mountain villages that rescue workers were still struggling to reach two days after the disaster. (Photo by Altaf Qadri/AP Photo)

Local villagers ride a local coal powered steam train on March 27, 2015 at a station in the town of Shixi , Sichuan Province, in Southern China. While China boasts the world's most extensive high-speed rail infrastructure with over 16,000 kilometers of track, the Shixi-Bagou railway is still a primary connection for local villagers between towns and is kept alive by tourist cars carrying passengers for ten times the price. The rail line came into service in the late 1950s and the train was initially used to transport coal from a now-shuttered mine before passenger carriages were added. (Photo by Kevin Frayer/Getty Images)