For centuries, people have been asking themselves what the source of the underground spring known as Fosse Dionne spring in France’s Burgundy region might be, but they never got to the bottom of it, because they literally couldn’t get to the bottom of it.
The Fosse Dionne is a huge upsurge of water around which the town of Tonnerre was built. For as long as anyone can remember it has been spewing massive amounts of water, with a flow of around 311 liters of water per second on a regular basis, which can increase to 3,000 liters per second in rainy weather conditions. The Romans used it for drinking water, the Celts considered it sacred, and the French used it as a public bathhouse during the 1700s, but no one has ever been able to locate its source. Many have tried, some have died trying, but the source of the Fosse Dionne remains a mystery.
