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)

Convicts showcase creations during a fashion show at female penal colony No 10 in the village of Gornoye, Primorye Territory, Russia on June 7, 2017. Prisoners of the colony sew clothes at a garment factory and every year they celebrate Day of Light Industry by presenting the clothes they made. (Photo by Yuri Smityuk/TASS)

Revellers enjoy air temperatures near freezing as they participate in the annual New Year's polar bear dip in the icy waters of Charlottetown harbour on Wednesday, January 1, 2020, in Charlottetown, Prince Edward Island. (Photo by Andrew Vaughan/The Canadian Press via AP Photo)

Natalie Portman and Tessa Thompson speak at the Marvel Studios Panel during 2019 Comic-Con International at San Diego Convention Center on July 20, 2019 in San Diego, California. (Photo by Kevin Winter/Getty Images)

The worst drought in 40 years has a cruel grip on Somalia. A struggling young government and militant violence have compounded to bring crisis to 6.7 million lives. The town of Baidoa is facing some of the harshest conditions. Surrounded by territory controlled by al-Shabaab militants and amid ongoing attacks, 160,000 people have had to leave their farms and are surviving in camps where hunger, thirst and cholera await them. (Photo by Peter Caton/Mercy Corps)

A general view of Hong Kong's business district is seen Thursday, August 1, 2013. (Photo by Vincent Yu/AP Photo)

Rescue operations are undergoing to recover the sunken ferry MV Miraj 4 in the Megna River near Munshiganj, Bangladesh, 16 May 2014. The death toll in the Bangladesh ferry disaster rose to 26 on 16 May, including children and women and many more feared dead as the ferry, carrying more than 200 passengers on board, sunk during a storm on 15 may 2014, police authorities said. (Photo by Abir Abdullah/EPA)

Del Mar firefighters roll up hose after a day fighting wildfires Wednesday, May 14, 2014, in Carlsbad, Calif. More wildfires broke out Wednesday in San Diego County, threatening homes in Carlsbad and forcing the evacuations of military housing and an elementary school at Camp Pendleton. (Photo by AP Photo)