There’s a lost continent waiting to be explored, and it’s right below our feet. We’ll dig into the deep human relationship to the underground—and why we understand it from an instinctive point of view, but not so much from a physical one. (Hint: We’re afraid of the dark.) In an episode originally published November 2021, National Geographic photographer Tamara Merino will take us subterranean in Utah, Australia, and Spain, where modern-day cave dwellers teach us how to escape the heat. For more information on this episode, visit natgeo.com/overheard. Want more? Go below ground with National Geographic Explorer Tamara Merino to see how these communities have been living—quite comfortably—for a very long time. In Vietnam photojournalist and National Geographic Explorer Martin Edström created 360 images of the world’s largest cave, Son Doong. It’s so big that a forest grows inside of it. Ever zip-line to a remote island? Cartographers did, 30 miles west of San Francisco. What did they see when they mapped the hard-to-reach landform known as the Farallon Islands? Caves. China is home to some of the most intricate cave systems on the planet. These explorers used a laser scanner to capture never before seen images of undocumented caves. Also explore: South Dakota is famous among cavers for its web of cave mazes. Take a look at what they’ve found under the Black Hills. Learn more about your ad choices. Visit megaphone.fm/adchoices