A woman dives and pretends to ride a bike in Underwater Park in Pula, Croatia, August 1, 2017. (Photo by Antonio Bronic/Reuters)

A Kamchatka Brown Bear cub eats frozen fruits during a Christmas feeding session at Hagenbecks zoo in Hamburg, northern Germany on December 5, 2014. (Photo by Fabian Bimmer/Reuters)

A Hawaiian cleaner wrasse provides its cleaning services to a yellowfin goatfish in a reef community off the Big Island in Hawaii. Cleaner species help rid their hosts of ectoparasites, dead tissue, bacteria and fungi. Studies have shown cleaning to play a vital role in keeping many reef ecosystems healthy. (Photo by Marty Snyderman/Caters News Agency)

A vendor sleeps at his vegetables shop at a main market in Colombo, Sri Lanka May 31, 2016. (Photo by Dinuka Liyanawatte/Reuters)

A vendor prepares paan, a betel nut-based chewable stimulant at a flower market in Kolkata, India, January 18, 2016. (Photo by Rupak De Chowdhuri/Reuters)

A vendor holds a fried spider along a street in Phnom Penh, Cambodia, April 10, 2017. (Photo by Samrang Pring/Reuters)

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)

Brian Skerry can be called many things – explorer, journalist, conservation advocate – but he is first and foremost a photographer. His journeys to capture amazing underwater photographs have taken him across the world’s oceans. Photo: This Bahamian oceanic whitetip shark, known for the distinctive coloring on its white-tipped, rounded extremities, is part of a globally threatened species due to overfishing demands, primarily for its fins. (Photo by Brian Skerry)