Mermaid Hales Parcells geets children as she performs at the Virginia Aquarium in Virginia Beach, Va., Monday, April 3, 2017. The Aquarium presents a mermaid show one night each week during the month of April. (Photo by Steve Helber/AP Photo)

South Korean students pose for a selfie following a traditional coming-of-age ceremony at Namsan hanok village in Seoul on May 15, 2017. The Coming of Age Day is the day to celebrate and encourage the youth who have reached the age of 20, which is considered the beginning of adulthood. (Photo by Ed Jones/AFP Photo)

Hotel staff practice self-defence skills after a training session given by team member of Special Weapons and Tactics (SWAT) team, in Hangzhou, Zhejiang province, April 7, 2016. (Photo by Reuters/Stringer)

Young gymnasts practice pull-up on a bar at a gymnasium of a sports school in Jiaxing, Zhejiang province April 11, 2015. (Photo by William Hong/Reuters)

A model presents a creation by Japanese designer Yoshikazu Yamagata for his label writtenafterwards during the Mercedes-Benz Fashion Week in Tokyo, Japan, 16 March 2016. The presentation of the Autumn/Winter 2016 collections runs from 14 to 19 March. (Photo by Kiyoshi Ota/EPA)

In this photograph taken on June 28, 2015, a hiker in Hong Kong takes a picture of the city from a walking trail. The southern Chinese territory is crisscrossed by more than 180 miles of designated hiking trails. (Photo by Alex Ogle/AFP Photo)

An Afghan man works at a traditional yarn factory in Heart province, Afghanistan July 28, 2015. (Photo by Mohammad Shoib/Reuters)