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)
Beautiful red sunset sky over Edinburgh, Scotland. Edinburgh is the capital city of Scotland and a popular tourist destination. It is also a major European financial (fund management) centre. Prominent buildings from left to right are: Edinburgh Castle, The Balmoral Hotel Clock Tower and The Scott Monument. (Photo by John Lawson/Getty Images)
A person holds an umbrella against strong wind and rain as he walks on a street Friday, June 2, 2023, in Kawasaki near Tokyo, as a tropical storm was approaching. (Photo by Eugene Hoshiko/AP Photo)
Children walk amid a mirror installation titled “Sea of Mirrors”, featuring digital images of fish in the ocean during a preview tour the day before the show's public opening at the AquaRio aquarium in Rio de Janeiro, Brazil, Wednesday, June 14, 2023. (Photo by Silvia Izquierdo/AP Photo)
The DFDS King of seaways enters the Mouth of the Tyne on the North East coast in Rough sea on Wednesday, January 18, 2023. (Photo by Owen Humphreys/PA Images via Getty Images)