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)

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)

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)

Russian President Vladimir Putin (R) looks through a window of a research bathyscaphe while submerging into the waters of the Black Sea as he takes part in an expedition near Sevastopol, Crimea, August 18, 2015. (Photo by Alexei Nikolsky/Reuters/RIA Novosti/Kremlin)

“Nature is beautiful and amazing – i just point my camera at it”. – Black Cat. Photo: “I really need a manicure”! (Photo by Black Cat)

Filipino barefoot Catholics carry a replica of the Black Nazarene during a procession ahead of the Black Nazarene feast day celebrations in Manila, Philippines, 07 January 2016. The procession of the Black Nazarene is expected to draw millions of barefooted Catholic devotees to Manila on 09 January, according to a Manila police official. (Photo by Francis R. Malasig/EPA)

Photographer Pol Kurucz’s vivid collection of photos explores issues faced by black Brazilian women, from political misrepresentation to unrealistic beauty standards. Kolor Collective is a Rio de Janeiro-based creative group that challenges the struggle faced by black women in Brazil through theatrical and provocative art. It was founded in 2015 by Franco-Hungarian photographer Pol Kurucz, who often touches on his own experiences of discrimination to call out sensitive social problems. (Photo by Kolor Art Collective/The Guardian)