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)

Casey Stoner of Australia and Repsol Honda Team rounds the bend during the third day of MotoGP testing at Sepang Circuit on February 2, 2012 in Kuala Lumpur, Malaysia. (Photo by Mirco Lazzari gp/Getty Images)

Fans of Croatia are seen during the UEFA Euro 2020 Championship Round of 16 match between Croatia and Spain at Parken Stadium on June 28, 2021 in Copenhagen, Denmark. (Photo by Antonio Bronic/Reuters)

Miss Panama Solaris Barba competes in the evening gown competition during the preliminary round of the 71st Miss Universe Beauty Pageant in New Orleans, Wednesday, January 11, 2023. (Photo by Gerald Herbert/AP Photo)

Eli Hanneman of Hawaii surfs in Heat 2 of the Round of 64 at the Ballito Pro on July 3, 2023 at Ballito, Kwazulu-Natal, South Africa. (Photo by Pierre Tostee/World Surf League via Getty Images)

Nic Lamb rides a wave during the third heat of the first round of the Mavericks Invitational big wave surf contest Friday, January 24, 2014, in Half Moon Bay, Calif. (Photo by Eric Risberg/AP Photo)

Two young boys kneel on stools on either side of a round table as one uses a match to this the other's cigarette, November 12, 1928. (Photo by FPG/Getty Images)

Street vendors hold campaign posters for presidential candidate Patrice Talon ahead of the second round of Benin's presidential election on Sunday in Cotonou, Benin, March 18, 2016. (Photo by Charles Placide Tossou/Reuters)