The 15 Coolest Caves in America

You can set up all the 50in televisions and kegerators you want, but your "man cave" is never gonna be as cool as the real caves Mother Nature creates. Sure, there's no hi-def or Sunday Ticket, but there ARE miles of rock formations, underground pools, and marble pillars. Plus, when summer gets its hottest, is there a better place to cool off than in Earth's own basement, where you can spend the afternoon in all-natural A/C surrounded by stalactites and stalagmites? (Tip: stalactites hang down from the ceiling, very tightly. Stalagmites come up from the ground and might someday reach the top. So you look cool on your nature walk.)

What, you'd still rather have the kegerator and Sunday Ticket? Whatever, be quiet. That's not an option, as these are the 15 coolest natural caves in America.

Harrison, AR
Sometimes known as the "Twin caves" since they sit about 400ft apart from each other, these two sinkholes deep in the Ozarks have more formations than any other cave in Arkansas' impressive collection. Once known as the "Mansion Cave" because it had so many giant rooms, Mystic Caverns is also home to the "pipe organ," a circular rock formation that looks like it could be used to introduce Count Dracula. Over in Crystal Dome, as the name might imply, you'll visit an eight-story dome made completely out of... onyx! What'd you think we were going to say, crystal?

Sonora, TX
About halfway between San Antonio and Big Bend National Park, well, there's a lot of open space that'll have anyone traveling I-10 saying, "Damn, we're STILL in Texas?" But a stop at these caves makes a nice break. Carved out of a massive limestone deposit by acidic water from an underground aquifer, the caves boast one of the most heavily concentrated collections of helictites in the world. The cool, two-mile walk will take you past the butterfly -- two helictites that share the same attachment point -- and the "snake pit," a room with so many twisting helictites, it looks like a pit of petrified... snakes! What'd you think we were going to say, onyx?

Centre Hall, PA
If hiking isn't your idea of communing with nature, then this is the cave for you. It's the only one completely navigable by motorboat, and the 45-minute tours float you through some of the most impressive stalactite and stalagmite formations in the Northeast. Legend has it that in the 1700s, local natives threw a French explorer in here to die after he fell in love with the chief's daughter, Nita-Nee. So it may be his ghost you hear yelling "NItt-Nee!" at the top of his lungs, or just some overzealous Penn State fans.

Mammoth Cave National Park, KY
While Southerners have never been shy about giving epic-sounding nicknames to things that aren't all that impressive, Mammoth Cave, located in Kentucky's Green River Valley, is actually one that lives up to the hype. It's the largest known cave network IN THE ENTIRE WORLD with over 400 miles of explored caves, including the famous "Bottomless Pit." Amazingly, new discoveries and cave connections are still being made.

Cave Junction, OR
As opulent as many an oligarch has tried to make their home by showcasing "halls of marble," none will ever live up to the real thing in these caves underneath the forest of the Siskiyou Mountains of southwest Oregon. Here, rainwater from the forests seeped underground and dissolved the marble, creating wide-open caves in the precious rock. In fact, it's one of only three caves in the United States to be made out of marble. The park runs multiple campgrounds and a chalet in which you can stay if you'd like to spend more than a day exploring.

Luray, VA
Maybe the greatest variety of formations and water features you'll see in any cave can be found in the Shenandoah River Valley. Starting with almost-white calcite formations packed so tightly, they look the creature's mouth from Alien. Or a bridal veil, if you believe the nickname they've been given. There are also towering stone columns that stretch the length of the massive chambers, as well as a 2ft-deep lake in the middle that reflects it all.

Glenwood Springs, CO
Aside from the fact that the caverns here are actually made from nature and not papier-mâché, you could almost say Glenwood is like the Disney World of American caves. The 150ft-deep King's Row is, by Glenwood's own admission, the most heavily decorated cave room in Colorado, with an extensive light show that highlights the most impressive formations. And once you're done exploring, there's an entire amusement park up top, complete with two roller coasters, a zip chair, and a swing that thrusts you out over the valley at 50 mph.

Carlsbad Caverns National Park, NM
If you've heard of only one cave in the United States, this is probably it. Here, you can explore the undersea world that used to be New Mexico, as prehistoric sea walls sit next to cacti and other desert shrubs in these caverns that formed when sulfuric acid devoured the limestone. The "Big Room," filled with the classic stalactite and stalagmite formations you've come to know and love, is the main draw, and you can spend a day exploring it by yourself. Or, you can hop on a ranger tour to get down and dirty/crawl through some of the lesser-explored 119 caves.

Griffith Park, Los Angeles, CA
No, they don't have any cool sulfuric acid-formed caverns in here. Nor do they have any pools of water. What they DO have is a giant computer that shows you everything going on in Gotham City and a whole armory of cool belt accessories. Or at least they do if you watched the 1960s-era Adam West Batman TV show; exterior shots of this cave were used as the home of the caped crusader. But you probably already knew this, and these other 14 cool facts about Griffith Park.

Harmony, MN
Throw everyone in your office a serious curveball when they ask you about your trip to Minnesota, and you tell them Niagara Falls was fantastic. Once you explain that you went to an underground waterfall in Niagara Cave, they'll go from thinking you're insane to being insanely jealous. An underground stream carved the passageways in this cavern -- some of the easier to walk of any cave trail you'll take -- and they lead to a subterranean 60ft waterfall, which, while not nearly as voluminous as Niagara Falls in New York, is still pretty impressive for something completely underground.

Custer, SD
No, the moniker here is not a tribute to a similarly named pop star's teeth, which may or may not resemble calcite rock formations. Rather, it was given when early 20th-century explorers discovered the cave and found the walls covered in shiny, spar crystals that, while not particularly valuable, are fascinating to look at. As are the even rarer hydromagnesite balloons, which look like little puffed-up rocks and are formed when gases inflated a pasty precipitation of magnesium carbonate hydroxide.

Sequoia National Park, CA
Though a trip to one of the 20 most popular national parks in America usually involves looking at giant, impressive feats of nature that sit ABOVE ground, if you'd like to see a part of the park that's not as well-known, head down to Crystal Cave. There, an underwater stream has polished the marble so finely that it looks like the lobby of a five-star hotel, assuming that lobby was also filled with stalactites and stalagmites. Just be warned: while Sequoia is open all year, you can only tour this canyon from May-November.

Jefferson County, MT
Although named after the legendary explorers, these lime-and-sandstone caves were used by Native Americans for hundreds of years before the US "discovered" them. Still, the deep caves in Montana's first state park are one of the area's top attractions, and the most extensive and impressive system of caves in the Northwest. The cave entrance sits atop a hill and offers sweeping views of the Jefferson River, and once inside, you'll be equally amazed by the floor-to-ceiling collection of water-formed rock structures.

Stanton, MO
Don't let the disco lights here fool you, this cave doesn't put on nearly the same kind of party as the river of the same name. But in a state called The Cave State, being the coolest kid in town is definitely cause for celebration. The largest commercial cave in Missouri not only features nifty light shows like the one pictured, but rooms so big, they have names like the "Theatre Room" (which, fittingly, boasts a wall of stalactites known as the "Stage Curtain"). Past the main rooms is a lower level that was discovered in the mid-20th century and reportedly served as a hideout for the legendary outlaw Jesse James.