Visitors cross the world's highest and longest glass-bottomed bridge above a valley in Zhangjiajie in China's Hunan Province on August 21, 2016. / AFP / FRED DUFOUR (Photo credit should read FRED DUFOUR/AFP/Getty Images)
Visitors cross the world's highest and longest glass-bottomed bridge above a valley in Zhangjiajie in China's Hunan Province on August 21, 2016. / AFP / FRED DUFOUR (Photo credit should read FRED DUFOUR/AFP/Getty Images)