Revellers take part in the annual “Naval Battle” of Vallecas in Madrid, Spain July 19, 2015. The slogan for this year's water battle is “Get wet for Alfon, freedom for Alfon”, referring to Alfonso Fernandez Ortega, a Vallecas resident who was sentenced to four years in prison in June. The festival was started spontaneously in 1981 when some neighbours started to throw water at one another due to high temperatures during the Virgen del Carmen Festival. (Photo by Juan Medina/Reuters)

A man takes a selfie next to a flooded street due to the overflowing of the Mapocho river during heavy rains in Santiago on April 17, 2016. Four million people in Santiago were without tap water Sunday after unusually heavy rain pounding central Chile triggered landslides that fouled the city's water supply and forced the closure of the world's biggest copper mine, officials said. (Photo by Martin Bernetti/AFP Photo)

Japanese team trains before the 6th FINA Synchronised Swimming World Trophy at the Water Cube on December 8, 2011 in Beijing, China. (Photo by Feng Li/Getty Images)

A helicopter drops water over a wildfire as a firefighter works to contain it in Benahavis, southern Spain, May 19, 2015. (Photo by Jon Nazca/Reuters)

An unexpected side-effect of the flooding in parts of Pakistan has been that millions of spiders climbed up into the trees to escape the rising flood waters. Because of the scale of the flooding and the fact that the water has taken so long to recede, many trees have become cocooned in spiders’ webs.

A man pours water on his camel on a hot summer day in Ahmedabad, India, May 18, 2017. (Photo by Amit Dave/Reuters)

People play with foam at a water park in Yantai, Shandong province, China June 16, 2107. (Photo by Reuters/Stringer)

A hyena kisses his own reflection while appearing to walk on water. (Photo by Jake De Wet/Caters News Agency)