In this March 22, 1975 file photo, a refugee clutches a baby as a government helicopter gunship carries them away near Tuy Hoa, Vietnam, 235 miles northeast of Saigon. They were among thousands fleeing from Communist advances. AP Photographer Nick Ut will be retiring from the AP in March 2017 after 51 years of taking photographs from the front lines of the Vietnam War to the red carpets of Hollywood. (Photo by Nick Ut/AP Photo)

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)

A Bosnian special forces soldier returns fire 06 April 1992 downtown Sarajevo as he and civilians come under fire from Serbian snipers. The Serb extremists were shooting from the roof of a hotel at a peace demonstration of some of 30,000 people as fighting between Bosnian and Serb fighters escalated in the capital of Bosnia- Hercegovina. (Photo by Mike Persson/AFP Photo)

A displaced Pakistani girl collects recyclable goods from a garbage to earn living for her family in Islamabad, Pakistan, Tuesday, January 19, 2016. (Photo by B.K. Bangash/AP Photo)

A woman chops a fish at her stall as a train passes by at a morning market near Duri train station in Jakarta in this February 12, 2009 file photo. (Photo by Reuters/Beawiharta)

In his series of untitled photographs Nobody Claps Anymore, the Mexican-American photographer Alec Dawson portrays ordinary people in their homes in a downbeat, ultra-stylised manner. Staring into space as they watch TV or water the garden, the real-life subjects of photographer hint at vast reserves of boredom and regret. (Photo by Alec Dawson)

A young Afghan vendor waits for customers to buy sheep's heads at a roadside stall at the busy market in Kabul on November 29, 2015. (Photo by Wakil Kohsar/AFP Photo)

A Shariah law official whips a woman who is convicted of prostitution during a public caning outside a mosque in Banda Aceh, Indonesia, Friday, April 20, 2018. Indonesia's deeply conservative Aceh province on Friday caned several unmarried couples for showing affection in public and two women for prostitution before an enthusiastic audience of hundreds. The canings were possibly the last to be carried out before large crowds in Aceh after the province's governor announced earlier this month that the punishments would be moved indoors. (Photo by Heri Juanda/AP Photo)