Indonesian mahouts clean their Sumatran elephant in a river near the zoo in Medan, North Sumatra, Indonesia, 12 December 2014. According media reports, the smallest of the Asian elephants, Sumatran elephant (Elephas maximus sumatrensis) is facing serious pressures arising from illegal logging and associated habitat loss and fragmentation in Indonesia. The population has come under increasing threat from rapid forest conversion to plantations. (Photo by Dedi Sahputra/EPA)

A devotee takes a holy bath in River Saali in Sankhu on the first day of Swasthani Brata Katha festival in Kathmandu January 5, 2015. During the month long festival, devotees recite one chapter of a Hindu tale daily from the 31-chapter sacred Swasthani Brata Katha book that is dedicated to God Madhavnarayan and Goddess Swasthani, alongside various other gods and goddess and the miraculous feats performed by them. (Photo by Navesh Chitrakar/Reuters)

These breathtaking images capture the hidden depths of one of the worlds largest caves, which is so big its home to a beach, a river and a jungle. At more than 130m high, and 150m across, the imposing cave is so big as high as the London Eye and wider than one-and-a-half football pitches. Here: The campers set up inside the cave on the beach. (Photo by Lars Krux/Caters News)

A scavenger sifts through garbage piled on the bank of Beirut river, Lebanon August 24, 2015. Lebanese protest organisers called for a fresh demonstration against the government on Saturday after two days of rallies that turned violent in central Beirut and wounded scores of people. The “You Stink” campaign has mobilised against the government's failure to solve a garbage disposal crisis, bringing thousands of people onto the streets in protests that have threatened the survival of the cabinet. (Photo by Mohamed Azakir/Reuters)

A Naga sadhu, or naked Hindu holy man, performs a ritual inside his tent during Kumbh Mela, or Pitcher festival, at Trimbakeshwar, India, Friday, August 28, 2015. Hindus believe taking a dip in the waters of a holy river during the festival will cleanse them of their sins. The festival is held four times every 12 years. (Photo by Rajanish Kakade/AP Photo)

Sculptures entitled “The Rising Tide” by British sculptor Jason deCaires Taylor are seen beside the River Thames in front of the Houses of Parliament and the London Eye ferris wheel in London, September 3, 2015. The representations of four horses and riders are fully visible at low tide but become immersed underwater twice a day as the Thames rises to reach full tide. The installation will be on display throughout September as part of the annual Totally Thames festival. (Photo by Toby Melville/Reuters)

A boy plays in a swollen creek under a bridge in Manila on October 16, 2016. Typhoon Sarika lashed the main Philippine island of Luzon on October 16, flattening homes and toppling trees and power pylons as more than 12,000 people fled to safer ground, officials said. Shanties built beside a river, under a creek are the usual victims of floodings. (Photo by Noel Celis/AFP Photo)

A bunker at aformer Swiss artillery fortress called Heldsberg stands near the town of St. Margareten, Switzerland March 22, 2015. Heldsberg fortress, located on the Swiss-Austrian border near the River Rhine and Lake Constance was built from 1938 to 1940 and remained in military use until 1992. Since 1993 it is open to the public as Fortress Museum Heldsberg. (Photo by Arnd Wiegmann/Reuters)