Mammoth Cave Passes 400-Mile Mark

New expeditions add 10 miles to world's biggest cave

Kentucky’s Mammoth Cave is a little more mammoth than previously thought.

The National Park Service announced last week that recent mapping expeditions in the cave system pushed its total length to over 400 miles—the distance between Baltimore and Boston.

"The expansion of the Mammoth Cave system in the last few years has been a matter of incremental additions to many parts of the cave rather than a single major discovery" said President of the Cave Research Foundation Charles Fox. "In recent years we have resurveyed sections of the cave so that we can produce more detailed maps that meet modern mapping standards, as well as exploring and mapping previously unexplored passages.”

Mammoth Cave, a web of connected caverns carved by the Green River into the western Kentucky limestone, underlies a national park of the same name which attracts 2 million visitors a year according to the NPS. It is the longest known network of caves in the world at more than twice the length of the runner up, South Dakota’s Jewel Cave.

Visitors can explore up to ten miles of the cave on a variety of tours, ranging from the advanced six-mile shimmy-&-climb, to the quarter-mile Frozen Niagara tour, open to families with kids under five.

Extended hours for spring begin March 23.