Explorers who are pushing the South West Boundary of Jewel Cave in the Black Hills continue to make major advancements after a big breakthrough earlier this year.
At over 170 miles Jewel is the third longest cave in the world – new passageways discovered in May have added almost two more miles to the cave.
In the most recent expedition in August cavers made the six and a half hour trek to the unexplored edge of the cave and pushed into a huge room they named the “Crushing Deep.”
