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)

Shortlisted: “Two big eyes” by Miao Yong (Zejiang province, China). Damselflies look over the leaves. “I was photographing insects in a park near my home when suddenly I found two damselflies in the grass. They kept flying and it was very difficult to focus until suddenly they parked behind a leaf”. (Photo by Miao Yong/2017 Royal Society of Biology Photographer of the Year)

Yakutsk, with a population of around 270,000, holds its own title: that of the coldest city on Earth. Here: Frost-encrusted house in the city centre. (Photo by Amos Chapple/Courtesy Images/RFE/RL)

Event entertainer Holly Egan poses with a guitar using an angle grinder as Kevin Jay and Nigel Cox spin burning steel wool, sending sparks flying under the A13 in Essex, UK on April 4, 2024. (Photo by Kevin Jay/Picture Exclusive)

Mexican training ship “Cuauhtemoc” moves past the Galata Tower in Istanbul, Turkiye on July 18, 2023. “Cuauhtemoc”, which was sent by the Mexican government as a sign of friendship between the two countries on the occasion of the 100th anniversary of the founding of the Republic of Turkiye, arrived at Sarayburnu Port. (Photo by Omer Faruk Yildiz/Anadolu Agency via Getty Images)

A surfer rides a large wave at El Bocal during the Vaca Gigante (Big Cow) giant wave surf competition in Santander, northern Spain December 17, 2016. (Photo by Vincent West/Reuters)

A bodyboarder rides a wave during a big- wave surfing session at Praia do Norte in Nazare on November 19, 2016. (Photo by Patricia de Melo Moreira/AFP Photo)

The aerial view shows terraced hills at Helin village in Anqing, in eastern China's Anhui province on January 12, 2024. (Photo by AFP Photo/China Stringer Network)