Dancers perform during the Opening Ceremony of the Rio 2016 Olympic Games at Maracana Stadium on August 5, 2016 in Rio de Janeiro, Brazil. (Photo by Jamie Squire/Getty Images)

A pilgrim prays at Mount Al-Noor, where Muslims believe Prophet Mohammad received the first words of the Koran through Gabriel in the Hera cave, ahead of the annual haj pilgrimage in the holy city of Mecca, Saudi Arabia September 7, 2016. (Photo by Ahmed Jadallah/Reuters)

An anti-coup protester holds a Burkinabe flag in Ouagadougou, Burkina Faso, September 18, 2015. Security forces in the capital of Burkina Faso fired in the air on Friday to disperse demonstrators who burned tyres and blocked neighborhood streets to protest at a military coup this week that derailed a democratic transition. The head of a military junta in Burkina Faso which took power on Thursday has freed interim President Michel Kafando and two of his ministers, state television said on Friday. (Photo by Joe Penney/Reuters)

A tourist struggles in the water, before standing up and wading away, after a wave strengthened by the influence of Typhoon Dujuan hit a river bank in Hangzhou, Zhejiang province September 29, 2015. (Photo by Reuters/China Daily)

People stand in the middle of the graves and in front of giant kites in the cemetery of Santiago Sacatepequez, Guatemala, November 1, 2015. Dating back 116 years, the tradition of flying kites in the cemetery of of Santiago Sacatepequez, integrates the Catholic feast of All Saints with ancient Mayan practices of honouring the dead. It is believed that the kites connect the living and the dead during the all saints day celebration. (Photo by Jorge Dan Lopez/Reuters)

Revelers dance and shout as they listen to music, in front of the main stage, during the 21st Woodstock Festival in Kostrzyn-upon-Odra, Poland July 31, 2015. An estimated 200,000 people attended the ongoing festival, a brainchild of Polish journalist and social campaigner Jerzy Owsiak, on Friday. Owsiak initiated the event to say thank you to those who donated money to his GOCC charity organisation that delivers medical care for children. (Photo by Kacper Pempel/Reuters)

(L-R) Playmates Monica Sims, Heather Rae Young and Hiromi Oshima attend the Playboy party with TAO at Spire Nightclub on February 4, 2017 in Houston, Texas. (Photo by Christopher Polk/Getty Images for Playboy)

Vietnam’s Son Doong cave, the largest in the world, could hold a 40-story skyscraper inside. The pristine ecosystem has its own river and jungle. Despite its size, Son Doong wasn’t discovered until 1991. It was lost again for nearly two decades and was fully explored for the first time in 2009. (Photo by Jason Speth/HuffPost)