Catherine, Duchess of Cambridge speaks to soldiers as she arrives at Calgary Airport on July 7, 2011 in Calgary, Canada. (Photo by Chris Jackson/Getty Images)

“For centuries, the Moken sea nomads have traveled the islands between Thailand and Myanmar fishing and foraging for food on the sea floor. Throughout the Mergui Archipelago, Moken migrate in flotillas of Kabangs (traditional boat of the Moken people), stopping at different islands and beaches. Expert freedivers, the Moken have adapted physically to an aquatic life, developing unique characteristics that let them see better and hold their breath longer while underwater”. – Taylor Weidman. Photo: Hook, an indigenous Moken man, holds a three-pronged throwing spear and searches for fish in the waters of Ko Surin National Park. March 1, 2013 – Ko Surin, Thailand. (Photo by Taylor Weidman/zReportage via ZUMA Press)

In this image made available by France's Marine Nationale, the cargo ship TK Bremen sits stranded on a beach near Erdeven, France, on December 16, 2011, spilled fuel oil fouling the water. (AP Photo/Mael Prigent, Marine Nationale)

Noriko Takatory of Japan shares a moment with her groom Moon Byung-nam of South Korea during an opening ceremony for upcoming mass wedding ceremony of the Unification Church at Cheongshim Peace World Centre in Gapyeong, South Korea, February 19, 2016. (Photo by Kim Hong-Ji/Reuters)

A boy jumps over a puddle of water on the outskirts of Havana, Cuba March 21, 2016. (Photo by Ueslei Marcelino/Reuters)

People walk during a polluted day in Shenyang, Liaoning province, March 31, 2016. (Photo by Reuters/Stringer)

Family members watch on as a bride and groom leave their house to be married in West Mosul on November 3, 2017 in Mosul, Iraq. Five months after Mosul, Iraq's second-largest city was liberated from ISIL in a nine-month long battle, residents have returned to the destroyed city to rebuild their lives. (Photo by Chris McGrath/Getty Images)

A woman wears a face mask in the part of the city near neighbourhoods known for burning coal for heating in Ulaanbaatar, Mongolia January 26, 2017. Not many people in Ulaanbaatar wear masks to protect themselves against pollution. (Photo by B. Rentsendorj/Reuters)