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)

Festival goers wear Australia day attire at Big Day Out 2012 at the Sydney Showground on January 26, 2012 in Sydney, Australia. (Photo by Mark Metcalfe/Getty Images)

Getting her tongue pierced was “exciting and scary” says a teen who succumbed to pressure from her best friend in Austin, Texas, February 22, 2008. This image is featured in National Geographic's exhibition “Women of Vision: National Geographic Photographers on Assignment”, on view at the Palm Beach Photographic Centre, Jan. 22 - Mar. 22, 2015. (Photo by Kitra Cahana/National Geographic)

These stunning pictures show a normally vicious tiger calmly swimming in a pool of algae, on Jule 9, 2014. The powerful cat takes a refreshing break by taking a dip in the bright green algae. But it looks like this big cat is scared of getting his head wet as he strains to keep it above the water. After splashing around for a bit the tiger gets out and tries to air-dry with specks of the vegetation dripping off his fur. The striking pictures were taken at Copenhagen zoo by snapper Soren Lundgren Neilson. (Photo by Soren Nielsen/Caters News)

A cyclist rides in al-Qudra desert in the Gulf emirate of Dubai, on June 8, 2020. (Photo by Giuseppe Cacace/AFP 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)

View of a group of ostriches, in the gardens of the Palacio do Alvorada, in Brasilia, Brazil, 02 June 2020. The ostrich is the largest and heaviest bird in the world. When the chicks hatch they are between 25 and 30 cm tall, weighing about 900 grams. (Photo by Joedson Alves/EPA/EFE/Rex Features/Shutterstock)

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)