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)

High-rise buildings are partly covered by heavy fog at Hong Kong's Victoria Harbour Monday, March 20, 2017. Fog blanketing Hong Kong is common in springtime and may greatly affect shipping and aviation. (Photo by Vincent Yu/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)

“The fantastic landscape of Bagan in Myanmar features hundreds of temples and pagodas as far as the eye can see. Experiencing this sight at dawn from the basket of a hot air balloon will remain engraved in my memory for ever. Mick Ryan, judge – What a magical photograph and place. The Buddhist temples and pagodas fill the plains of Bagan in Myanmar at sunrise… the golden hour providing beautiful light to illuminate the retrogression of the temples and balloons toward a misty, mountainous distance. An excellent, exotic photograph that makes you want to book a flight”. (Photo by Alastair Swan/The Guardian)

The Aurora Borealis (Northern Lights) is seen over the sky near the village of Pallas (Muonio region) of Lapland, Finland September 8, 2017. (Photo by Alexander Kuznetsov/Reuters)

A woman applies lipstick in a car that is parked at a beach facing a volcanic rock called Devil's Finger outside Yuzhno-Kurilsk, the main settlement on the Southern Kurile island of Kunashir September 15, 2015. Russian residents of the island chain at the centre of a dispute between Japan and Russia that has held up a treaty to formally end World War Two hope a diplomatic solution will lure tourists and investment to help refurbish rickety infrastructure. The Southern Kuriles are referred to in Japan as the Northern Territories. (Photo by Thomas Peter/Reuters)

Talk about being in the eye of the storm! These stunning snaps show breath-taking storms from an extraordinary up-close perspective. Taken by daredevil storm chaser Dennis Oswald, from Neuss, Germany, the amazing pictures capture spectacular storms from around the globe. Having chased storms for nearly 15 years, experienced Dennis gets right in the action to get these incredible shots. Here: scenic mothership supercell just north of Howard, Kansas. (Photo by Dennis Oswald/Caters News)

This picture taken on November 9, 2014 shows sharks for sale as a man removes the fins at a traditional market in Tanjung Luar in Lombok, West Nusa Teggara. Hundreds of sharks are hauled ashore every day at a busy market on the central Indonesian island of Lombok, the hub of a booming trade that provides a livelihood for local fishermen but is increasingly alarming environmentalists. The fins are sold to other Asian nations, including Singapore, Hong Kong and Taiwan, where shark-fin soup is considered a delicacy. (Photo by Sonny Tumbelaka/AFP Photo)