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)

Gray whale feeding at the surface and showing it's baleen. (Photo by Christopher Swann/Biosphoto)

Jellyfish with a juvenile imperial blackfish (Schedophilus ovalis) in Castellammare di Stabia, Naples, Italy, winter 2023. (Photo by Marco Gargiulo/Media Drum Images)

Sunderland’s Granit Xhaka in action with AFC Bournemouth’s Bafode Diakite in Sunderland, UK on November 29, 2025. (Photo by Scott Heppell/Reuters)

Bangladeshi Muslim devotees arrive in an over-crowded train to attend the final day of an Islamic congregations' first phase in Tongi, 20 kilometers (13 miles) north of Dhaka, Bangladesh, Sunday, January 10, 2016. The second phase of the annual event, one of the world's largest congregations of Muslims is scheduled to begin Friday. (Photo by A.M. Ahad/AP Photo)

Miss Universe contestant Carolina Duran of Costa Rica, center, reacts to a TV network's drone as others prepare to pose from the deck of the yacht Happy Life prior to cruising to a beach resort in Batangas province Thursday, January 19, 2017 at the Philippine Navy headquarters in Manila, Philippines. Eighty-six candidates from around the world are vying for the title to succeed Pia Wurtzbach from the Philippines. The competition takes place on Jan. 30. They are, from left, Cherell Williamson of Bahamas, Rebecca Rath of Belize, Hildur Maria of Iceland, and Chanelle de Lau of Curacao. (Photo by Bullit Marquez/AP Photo)

A model wears a creation for the Stephane Rolland Spring-Summer 2022 Haute Couture fashion collection collection, in Paris, Tuesday, January 25, 2022. (Photo by Francois Mori/AP Photo)

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)