Located in Crawford County, Missouri, is a hidden state treasure – literally! Just off the Meramec River, deep underground, is an incredible state park within a natural cave system, and it’s begging for you to visit.

The Onondaga Cave State Park is an incredible cave with seemingly endless things to explore.
Matt Lehrer/Flickr
Discovered by a local named Charles Christopher in 1886, the cave was named for an Iroquois tribe in 1904. The name "Onondaga" roughly translates to "people of the hills".
Stalactites dangle similarly to icicles. They often stretch downward to meet their inverted siblings, stalagmites, forming awe-inspiring columns.
Matt Lehrer/Flickr
It is important to remember to look, but never touch these incredible geologic treasures. They grow at a pace so slow that should one be taken by a visitor to the cave, it will not grow back within a human lifetime. Possibly even several human lifetimes!
The Onondaga Cave State Park lies alongside the Meramec river, one of the longest free-flowing rivers in the United States.
Kbh3rd/Wikimedia
The river gives life to local wildlife, some of whom manage to find their way into the caves. They must be rescued by park rangers or they will not likely survive within the cavern. The life within the cave has evolved over hundreds of thousands of years to thrive in the dark, damp environment.

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Denizens of the cave include various types of amphibians and fish, many of whom lack functioning eyes. Eyesight is not necessary in the world they're accustomed to.
Jeffrey Grandy/Flickr
The cave itself is an active, "living" cave. It is constantly in a state of change, both by natural processes and by human activity. The changes are incredibly minute and subtle, and would take lifetimes to physically notice.
Visitors can book one of any number of guided tours of the cave, and there's a designated campground nearby (though not in the cave itself.)
Dave Thomas/Flickr
The campgrounds offer everything from bare-bones "primitive" camp sites to more modern options, including electricity. The campsites offer access to the river, and are in nearby proximity to the cave. From April through October, reservations are required to camp at the park.
The cave is full of cool, still water. Some pools are so still that calcite crystals gather on the surface and form structures called "lily pads," which sink at the very first sign of water movement.
Dave Thomas/Flickr
Some daring adventurers can explore the cave by boat, though of course, a guide is still important.
The Onondaga Cave State Park is an absolutely unforgettable but often overlooked state treasure.
Dave Thomas/Flickr

If you’d like to reserve your camping spot at the Onondaga Cave State Park, you can do so here. Always remember to leave no trace, and do your part to keep this park beautiful for generations to come.

Have you ever been spelunking in an underground cave? What was it like? Tell us all about it in the comments! Check out our previous article for more caves in Missouri.

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