Plunging 103 meters underground, this chasm features a series of wild geological formations that are the result of a subterranean river gradually sculpting its limestone surroundings. Visitors can descend by an elevator and a series of steps and then wander the labyrinth by foot and by guided boat. The visit features the Salle du Grand Dôme, a 94-meter chamber big enough to fit the Notre Dame Cathedral.
Chris O'Brien is an American journalist living in Toulouse, France. He moved with his family to France in 2014 after spending 15 years covering Silicon Valley for the San Jose Mercury News and Los Angeles Times. Currently, he freelances and covers startups, entrepreneurs, and technology for publications such as VentureBeat, Les Echos' The Innovator, and the LA Times.