India's Central Reserve Police Force personnel take part in a rehearsal for the Republic Day parade on a cold winter morning in New Delhi January 8, 2014. (Photo by Ahmad Masood/Reuters)

Cha Huilan, a 40-year old Lisu woman, and her daughter leave Lazimi village with a zipline across the Nu River in Nujiang Lisu Autonomous Prefecture in Yunnan province, China, March 24, 2018. Chinese mountain villagers, cut off from shops and churches by a raging river, use a zipline to cross its violent rapids and jagged rocks. (Photo by Aly Song/Reuters)

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)

A freediver uses weights, yoga and camera tricks to create the illusion of walking underwater for a film which took three years to shoot and was completed in 2013 in El Hierro, Canary Islands. Like a scene from a Hollywood science-fiction movie, this trick footage shows a man apparently walking on water. The underwater film was shot by biologist Armiche Ramos and brothers Armando and Francisco del Rosario, who used their expertise in freediving to create the illusion. No computer graphics were involved in the production, with the team relying solely on their own skills – and a few hidden secrets. (Photo by Ocean Brothers/Barcroft Media/ABACAPress)

Stunning images taken by Sean Lenz, 19, and Kristoffer Abligaard, 20, show picturesque waterfalls transformed into vibrant rainbows of colour. The awe-inspiring images were created by clever use of long exposure photography and glow sticks floating through water. Photo: Picturesque waterfalls transformed into rainbows of colour. (Photo by Sean Lenz/Kristoffer Abildgaard)

Israelis in costumes spray water on each other during the annual Tel Aviv Water War on Hbima Square in Tel Aviv, Israel,10 July 2015. The annual water fight is on his 11th edition. (Photo by Abir Sultan/EPA)