Kentucky's Mammoth Cave was already the longest cave system in the world.
"THE LONGEST CAVE IN THE WORLD IS NOW EVEN LONGER!!!" Mammoth Cave National Park announced on Facebook over the weekend.
An additional 8 miles of passages were mapped and explored by the nonprofit Cave Research Foundation, according to the park, which has worked with foundation volunteers for years to document newly discovered areas of Mammoth Cave.
The cave system's known length now stands at 420 miles, and the park says "there is no end in sight."
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This article originally appeared on USA TODAY: Mammoth Cave adds 8 newly mapped miles to its already record length