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)

Residents wade through flood waters from Tropical Storm Harvey in Beaumont Place, Houston, Texas on August 28, 2017. Houston was still largely paralyzed Monday, and there was no relief in sight from the storm that spun into Texas as a Category 4 hurricane, then parked itself over the Gulf Coast. (Photo by Jonathan Bachman/Reuters)

A man throws water at pedestrians as residents join in a water-splashing frenzy to honor their patron Saint John the Baptist's Feast Day in San Juan, Metro Manila, Philippines June 24, 2016. San Juan is renowned for its celebration of the Nativity of St. John the Baptist every year of June 24. In a nod to the saint's characteristic act, San Juaneños engage in Basaan (“wetting”), where revellers splash people with water. (Photo by Romeo Ranoco/Reuters)

People attend the Stranavigli Water Race held at the Naviglio Grande on July 16, 2011 in Milan, Italy. Stranavigli Water Race is an annual creative contest on the water. (Photo by Vittorio Zunino Celotto/Getty Images)

“The Portuguese Water Dog is a breed of working dog as classified by the American Kennel Club. Portuguese Water Dogs are originally from the Portuguese region of the Algarve, from where the breed expanded to all around Portugal's coast, where they were taught to herd fish into fishermen's nets, to retrieve lost tackle or broken nets, and to act as couriers from ship to ship, or ship to shore. Portuguese Water Dogs rode in bobbing fishing trawlers as they worked their way from the warm Atlantic waters of Portugal to the frigid fishing waters off the coast of Iceland where the fleets caught cod to bring home. Portuguese Water Dogs were often taken with sailors during the Portuguese discoveries”. – Wikipedia

Photo: Kix, a Portuguese Water Dog , enjoys a walk around the muddy fields near his home before the grooming and preparation starts for this years Crufts on March 3, 2009 in Telford, England. (Photo by Christopher Furlong/Getty Images)

Mom dressed as Santa and a boy dressed as Santa's helper posing under the water in the pool on December 15, 2016 in Odessa, Ukraine. (Photo by Andrey Nekrasov/Barcroft Images)