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)

Sri Lankan military personnel march during the country's 66th Independence Day celebrations in the central town of Kegalle, about 40 kms from the capital Colombo on February 4, 2014. Sri Lanka cemmemorates its independence from British rule on February 4, 1948. (Photo by Ishara S. Kodikara/AFP Photo)

The lightest material ever made has been produced by a team of scientists in China, a Chinese university announced.

A couple watch the sunrise in front of the Mediterranean Sea in Barcelona, Spain, Sunday, January 24, 2021. (Photo by Emilio Morenatti/AP Photo)

Yi Arias, a CORE crew member in an upbeat mood at COVID-19 mass-vaccination of healthcare workers taking place at Dodger Stadium in Los Angeles, California, U.S., January 15, 2021 (Photo by Irfan Khan/Pool via Reuters)

Children run next to a paraglider wearing Santa Claus costume landing to deliver gifts to refugee children from Karabakh region, near the village of Akunk, outside Yerevan, on December 26, 2023, as part of “ParaSanta”, an event organised by the Armenian Paragliding Club. (Photo by Karen Minasyan/AFP Photo)

Participants in the 3rd Annual Amber Rose SlutWalk in Los Angeles, California. October 1, 2017. The event seeks to highlight issues such as: gender equality, ending rape culture, victim blaming and body shaming. (Photo by Ronen Tivony/NurPhoto via Getty Images)

The Lake of Lights at Talkin Tarn lake near Brampton in Cumbria, England on October 22, 2017 – where hundreds of lights in the surrounding woodland represent a cherished memory of a relative friend or loved one no longer with us. (Photo by Owen Humphreys/PA Images via Getty Images)