These two young siblings appear to cling on to a tree for dear life and even hold hands as they learn the ropes of climbing, on June 25, 2013. (Photo by Tim Fitzharris/Minden/Solent)

Rickshaw drivers wade through a flooded road after heavy rains swept through Guwahati, in the northeastern Indian state of Assam, on June 26, 2014. Seven people have been killed there in flash floods, landslides and heavy rainfall, local media reported Friday. (Photo by Utpal Baruah/Reuters)

Ary Borges feeds his tiger named Dan at his home in Maringa, Brazil, Thursday, September 26, 2013. Borges is in a legal battle with federal wildlife officials to keep his endangered animals from undergoing vasectomies and being taken away from him. He defends his right to breed the animals and says he gives them a better home than they might find elsewhere in Brazil. (Photo by Renata Brito/AP Photo)

Bangladeshi fisherman feed their otters as they catch fish in Narail some 208 kms from Dhaka on March 11, 2014. The fishermen are using a rare technique that relies on coordination between man and trained otters, a centuries-old fishing partnership that has already long died out in other parts of Asia. (Photo by Munir Uz Zaman/AFP Photo)

A South Korean marine in action during their regular drill on Yeonpyeong Island, South Korea November 1, 2018. (Photo by Jeon Heon-Kyun/Pool via Reuters)

Spectators pose for a selfie before the running of the Melbourne Cup at the Flemington Racecourse in Melbourne, Australia, Tuesday, November 6, 2018. (Photo by Andy Brownbill/AP Photo)

The singing group The D-Day Darlings take part in the unveiling ceremony of a permanent war memorial, created by artist and writer Fabian Peake, at St Pancras International railway station in London, Britain, November 8, 2018. (Photo by Peter Nicholls/Reuters)

A visitor is reflected in a light installation at Mulberry Lights on Regent Street in London, UK on November 16, 2018. Visitors have fun taking selfies and posing with the colourful light installations. Mulberry Lights is a series of illuminating interactive experiences that celebrate how light, colour, shapes and people come together to create a modern British Christmas. (Photo by Imageplotter/Rex Features/Shutterstock)