Let’s put it this way: it is 388 miles to drive between Los Angeles and San Francisco. Imagine being in a cave that whole way, and still not having the exit in sight. That is what makes Mammoth Cave unique.

Mammoth Cave National Park protects a bit more than 52,000 acres of central Kentucky, but while the forested hills are lovely, it isn’t what is on the surface that draws visitors. Rather, it is what lies under the surface that is of interest: the world’s longest cave system, with more than 400 miles of explored and mapped passageways, and more being discovered yearly.

Caves are awesome!

Caves normally develop in limestone, where water is able to erode passageways over time – many millions of years. Combined with a top layer – in this case sandstone – which is difficult for water to penetrate, and those passageways develop into large caverns. Many of the passages in Mammoth Cave look like subway tunnels, and are relatively unornamented, while others have developed limestone features (stalactites and stalagmites, and other ornamentation) that is normally associated with caverns of this magnitude. Other passageways are home to underground river systems.

A relatively unadorned tunnel… these are the norm.

This part of Kentucky is known for caves. Over the past century, many “separate” caves, like the Flint Ridge Cave System, have been traced to actually be part of Mammoth Cave. As such, the Cave has many entrances, although few are open to the public – and many aren’t even large enough for easy access. It is expected, although not a guarantee, that the nearby Fisher Ridge Cave System – which itself has been mapped to 125 miles – will also connect with enough exploration.

Your day at Mammoth Cave National Park will begin at the Visitors Center. You will, of course, have made your tour reservation ahead of time, as the cave system isn’t able to be seen without a booked tour. Normally, it is by guided tour only; however, in Covid times, a self-guided option is the only one available, following the Extended Historic Tour. While here, walk to the Historic Entrance, the so-called front door of Mammoth Cave, from which the system was explored originally. You won’t be going in this way. Rather, you’ll be going in at one of the other entrances, depending on which tour you’ve booked.

The Extended Historic Tour will take approximately 90 minutes, and will include some fairly slippery walking, steps, and limited lighting in places. When running, other options for guided tours range from short to incredibly long, seeing different portions of the Mammoth Cave System. One of my favorite portions from my trip several years ago was Frozen Niagara, a large limestone ornament that looks like a huge frozen waterfall.

Frozen Niagara

While not as visually stunning as another cave national park, Carlsbad Caverns, Mammoth Cave is probably easier to see given its location about halfway between Louisville and Nashville, and an easy day trip from either one. Plus, while rooms aren’t as large as the Big Room at Carlsbad, nor as “decorated,” it’s pretty cool to be inside the world’s longest cave, though the sheer scope of it is hard to grasp.

These look like tree roots.

Make sure to wear comfortable shoes (and you’ll need to go through a self-washing station for your shoes following your tour to get rid of any contamination) and a sweatshirt (it can be chilly inside the cave no matter the weather outside). Also, be sure to watch both your step (it can be slick in places as water is actively seeping in) and your head, as there are low hanging rock formations that can cause a nasty blow.


And then head out out to the Bluegrass State, and the world’s longest cave system. You won’t be disappointed!

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