Andrey Karr from Western Riders Slacklines at sunset above big waves in Nazare, Portugal on December 27, 2017. (Photo by Aidan Williams/National Geographic Travel Photographer of the Year Contest)
A man plays in front of a wave crashing into Beirut's Corniche, a seaside promenade, as high winds sweep through Lebanon ahead of an impending storm January 6, 2015. (Photo by Jamal Saidi/Reuters)
A Ukrainian serviceman wearing a new year's hat waves at his comrades while standing beside his tank near Debaltseve, eastern Ukraine, February 8, 2015. (Photo by Gleb Garanich/Reuters)
North Korean children wave to people on a Chinese tourist boat on the banks of Yalu River near the Chongsong county of North Korea, opposite the Chinese border city of Dandong, May 8, 2011. (Photo by Jacky Chen/Reuters)
People with a South Korean flag waves as fireworks get off outside the stadium during the opening ceremony of the Pyeongchang 2018 Winter Olympic Games at the Pyeongchang Stadium on February 9, 2018. (Photo by Martin Bernetti/AFP Photo)
North Koreans wave flower bouquets and balloons as they march during a parade at the Kim Il Sung Square on Tuesday, May 10, 2016, in Pyongyang, North Korea. (Photo by Wong Maye-E/AP Photo)
A bodyboarder rides a wave at Mackenzies Bay on May 1, 2011 in Sydney, Australia. A strong east-south-east swell has developed along the NSW coastline with waves between 6ft and 8ft expected to hit the coast for much of the weekend and into next week. (Photo by Cameron Spencer/Getty Images)