Mystery of the Lost River – Produced by Chet Hedden. Videography by Dave Socky. 44:56 minutes

On January 2, 1960, two cave explorers from Ohio crawled under a ledge in the longest cave in the world and discovered a deep canyon with a flowing stream.

Two months later another caver from Ohio accompanied one of the original discoverers on a return visit to the canyon. The passage continued in both directions. Upstream was a small waterfall, and behind that a clear pool.

That was the last time anyone visited the canyon with the flowing stream. Later exploring parties could not find it.

Decades later a team of geoscientists tried to locate the “Lost River” by detecting variations in the force of gravity in the passage above the area where the canyon is known to exist. It was the first time ever that a micro-gravity profiling survey was attempted deep inside a cave. This is the story of the attempt to find the “Lost River”.