A boy shouts after catching a trout during a trout catching contest in Hwacheon, South Korea, Saturday, January 6, 2018. The contest is part of an annual ice festival which draws over 1,000,000 visitors every year. (Photo by Ahn Young-joon/AP Photo)

A man wearing a Guy Fawkes mask enjoys a ride on a 350-meter (1148 feet) long water slide during 2015 City Silde Festa in central Seoul, South Korea, July 19, 2015. A 350 meter-long waterslide has been installed in downtown of Seoul, the longest waterslide to be recorded in Korea, according to local media. (Photo by Kim Hong-Ji/Reuters)

Planes land in fog at Heathrow Airport, west London on January 4, 2014, as heavy fog covers a many parts of the south east. (Photo by Steve Parsons/PA Images via Getty Images)

Crew members work to secure a hot-air balloon after landing at the city of Luxor, south of Cairo, Egypt December 13, 2016. (Photo by Amr Abdallah Dalsh/Reuters)

An Airbus A400M military aircraft lands at the ILA Berlin Air Show in Schoenefeld, south of Berlin, Germany, June 1, 2016. The Aerospace Exhibition at Schoenefeld Airport near Berlin takes place from June 1 till 4. (Photo by Fabrizio Bensch/Reuters)

Planes land in fog at Heathrow Airport, west London, as heavy fog covers a many parts of the south east, on April 1, 2014. (Photo by Steve Parsons/PA Wire)

A large sand sculpture is seen at the site of Yokohama Sand Art Exhibition – Culture City of East Asia 2014 on July 16, 2014 in Yokohama, Japan. Producer and sand sculptor Katsuhiko Chaen invited artists from around the world including South Korea and China, to recreate the World Heritage and historical buildings in China, Japan and South Korea. The exhibition will be open from July 19 to November 3, 2014. (Photo by Chris McGrath/Getty Images)

South Korean rescue members wearing chemical protective suits walk past a monster character (R) during an anti-terror drill as part of a disaster management exercise at the COEX shopping and exhibition center in Seoul on May 20, 2016. South Korea is holding its 2016 Safe Korea anti-disaster exercise this week against terrorist threats and natural disasters. (Photo by Jung Yeon-Je/AFP Photo)