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)

Palestinians watch a man performs acrobatics on the beach of Gaza City, Friday, June 4, 2021. (Photo by Khalil Hamra/AP Photo)

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

A dog sits in a plastic basin filled with water in Taipei, Taiwan, 05 May 2018. Betel nut seller Mr Luo, the dog's owner, said he puts his dog Ah Dai (Stupid Guy) in the water-filled basin whenever the weather get hot. Luo has a dozen pairs of glasses for Ah Dai, so the dog wears different glasses every day and many tourists take photos of Ah Dai. (Photo by David Chang/EPA/EFE)

Blizzard in the High Peak, Derbyshire, by John Finney: “After a difficult journey in the snow, I made my way from Mam Tor down onto the Great Ridge. As the clouds got darker, I placed the tripod and camera at just the right angle to avoid snow getting onto the lens, and used a flash gun and a relatively slow shutter speed to highlight the fast motion of the blizzard”. Classic view, adult class – winner. (Photo by John Finney/Landscape Photographer of the Year)

A woman applies lipstick in a car that is parked at a beach facing a volcanic rock called Devil's Finger outside Yuzhno-Kurilsk, the main settlement on the Southern Kurile island of Kunashir September 15, 2015. Russian residents of the island chain at the centre of a dispute between Japan and Russia that has held up a treaty to formally end World War Two hope a diplomatic solution will lure tourists and investment to help refurbish rickety infrastructure. The Southern Kuriles are referred to in Japan as the Northern Territories. (Photo by Thomas Peter/Reuters)

A dancer poses for a photograph as part of the “Dance as Art” photo project in Times Square in New York, on September 22, 2014. (Photo by Carlo Allegri/Reuters)