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Hang Son Doong: The world's biggest cave, so 'outrageous in size' it fits 2 jungles and the 'Great Wall of Vietnam'Vietnam's Son Doong cave is so large, you could squeeze 15 Great Pyramids of Giza inside it and fly a Boeing 747 airplane through some of its passages.
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Diamond Beach: Iceland's spellbinding black sand beach covered in sparkling ice jewelsIcebergs and other glacial fragments regularly wash up on Iceland's southern Diamond Beach, making the sandy strip look like a field of gemstones.
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Carlsbad Caverns: New Mexico's otherworldly caves with gypsum flowers and 'soda straws' dangling from the ceilingCarlsbad Caverns National Park in southeastern New Mexico is home to 119 known caves, including North America's largest cave chamber, the Big Room.
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Hranice Abyss: The deepest freshwater cave on Earth and a conduit to a 'fossil' sinkholeScientists first described the flooded cave in 2016 but determined its extraordinary extent years later.
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Nazaré: The big-wave surfer's paradise born out of the largest underwater canyon in EuropeEvery year, record-seeking surfers and spectators descend on the small Portuguese town of Nazaré for the "big wave" season, when water can surge up to 100 feet (30 meters) tall.
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Rainbow swamp: The flooded forest in Virginia that puts on a magical light show every winterEvery winter, when sunlight hits at the right angle, visitors to Virginia's First Landing State Park are treated to a mesmerizing rainbow light show courtesy of the park's bald cypress swamp.
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Gateway to the underworld: The enormous permafrost 'megaslump' in Siberia that keeps getting biggerThe growing "gateway to the underworld," officially known as the Batagay megaslump, is the largest megaslump in the world and exposes permafrost layers that are 650,000 years old.
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White Shark Café: The mysterious meeting spot for great whites in the middle of the Pacific OceanEvery winter and spring, great white sharks that usually dwell off the coast of California gather in a remote section of ocean the size of Colorado — and scientists are slowly piecing together why.
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Al Naslaa rock: Saudi Arabia's enigmatic sandstone block that's split perfectly down the middleAl Naslaa is a rock formation in Saudi Arabia's northwestern desert consisting of two huge, symmetrical stone blocks that are separated by a mysterious gap and sit on small pedestals.
