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)

Naked activists take part in a protest against fur trade, called by international non profit animal rights organisation AnimaNaturalis, in Barcelona, on December 1, 2019, on the eve of the opening of the UN Climate Change Conference COP25. (Photo by Pau Barrena/AFP Photo)

An Iranian girl walks at the Tochal ski resort, in north of Tehran, Iran on December 12, 2019. (Photo by Nazanin Tabatabaee/WANA via Reuters)

Revellers take part in the annual block party known as “Casa Comigo” (Marry Me), during carnival festivities in Sao Paulo, Brazil on February 15, 2020. (Photo by Rahel Patrasso/Reuters)

Inside the new Digital Art Museum in Tokyo, Japan on June 21, 2018. These incredible photos show what it looks like inside a groundbreaking new digital art museum in Japan. A trip to the Mori Building Digital Art Museum: teamLab Borderless in Tokyo, which opened last week, can make you feel like they you are dreaming and aims to fully immerse visitors in the art. Spanning a spacious 10,000 square metres, 520 computers and 470 high-tech projectors create the illusion that the visitor is wandering through rice fields, following shoals of fish or even bouncing on a galaxy of planets. (Photo by South West News Service)

A Kenyan model Ajuma Nasanyana waits behind the scenes before the fashion show showcasing African fashion and culture during a gala marking the launch of a book called “African Twilight: The Vanishing Rituals and Ceremonies of the African Continent” at the African Heritage House in Nairobi, Kenya on March 3, 2019. (Photo by Baz Ratner/Reuters)

The Golden Gai is a sliver of old Tokyo in a modern metropolis filled with endless gleaming buildings. It's a one-of-a-kind tourist attraction, for sure. But it's also a place for a few drinks and friendly chatter among exhausted workers known as “salarymen”. Here: A man strolls through a narrow alleyway clustered with tiny bars and restaurants at the Golden Gai in the Shinjuku district of Tokyo, July 17, 2019. (Photo by Jae C. Hong/AP Photo)

Catholic faithfuls hold figurines of baby Jesus during a religious procession on Holy Innocents Day in Antiguo Cuscatlan, El Salvador, December 28, 2016. (Photo by Jose Cabezas/Reuters)