(MONEY Magazine) – Let's start with the disclaimer: If you're claustrophobic, this might be a good time to turn to the next article. But for everyone else, here's an idea for your spring travel planning: Visit a cave.

A dank underground cavity might not initially seem appealing, but caves and tourism have long been intertwined. Lantern-lit tours of Mammoth Cave in Kentucky began in the early 1800s, and about 200 more show caves--the industry term for caves open to the public--have opened in the United States since then (for current listings, go to cavern.com). And why not? With their surreal formations and winding crevices, caves are a bizarre parallel world literally just under our feet. Many of them have fascinating histories, having served as speakeasies, nightclubs and even TV studios. And thanks to their year-round temperatures of about 55°F, caves hosted all sorts of events in the days before air conditioning, including community meetings and dances. Several of them continue to host weddings!

If you're thinking, Been there, done that because you took a field trip in second grade, think again. Kids certainly love caves, but it takes the jaded sensibility of an adult to fully appreciate how remarkable these spaces are. And I should know: The main thing I recall from a childhood trip to Luray Caverns (Rte. 211, Luray, Va.; 540-743-6551; luraycaverns.com) is that I wanted the tour to finish so we could have lunch already. But when I went back to Luray this past winter, I was blown away by the stalactites (the formations that hang down from the ceiling), stalagmites (the ones that grow up from the floor) and other structures. After touring a dozen more caves over the following month, I was still oohing and ahhing.

Some cave bacon with that?

Marketing hype notwithstanding, most show caves are fairly similar. But Luray, which has an unusually broad range of formations, is my favorite. Like most caves, it's a lighting designer's dream, with countless crannies and ridges that interact with light and shadow to extremely dramatic effect. America's first air-conditioned home was built right atop the cave in 1901, with cool cave air pumped in through a connecting shaft. And Luray also features the Great Stalacpipe Organ, a musical keyboard wired to rubber-tipped mallets that strike a series of pitch-tuned stalactites. Billed as the world's largest musical instrument, it's cheesy but irresistible.

The same geological conditions that create one cave (usually ancient rivers eroding soft layers of subterranean limestone) tend to create lots of them in the same region. Of the many show caves in Virginia's Shenandoah Valley--one of which is called Endless Caverns, neatly summarizing the area's tourism culture--the best backup to Luray is Shenandoah Caverns (261 Caverns Rd., Shenandoah Caverns; 540-477-3115; shenandoahcaverns.com), which has particularly gorgeous "cave bacon"--striated formations that look remarkably like breakfast pork.

A heritage of hucksterism

Although officially nicknamed the Show Me State, Missouri is also called the Cave State, a reference to its roughly 6,000 caves, 23 of which offer tours. The state's crown jewel is Meramec Caverns (Exit 230 on I-44, Stanton; 800-676-6105; americascave.com), once a classic Route 66 tourist trap. That heritage of hucksterism endures today in the innumerable billboards with which Meramec's owners have wallpapered the I-44 corridor, many featuring sales pitches of endearingly dubious appeal ("Part of Missouri's History!" or "Jesse James Hideout!" or "Lunch Specials Daily!"). The tour gets a bit hokey too: The guides love pointing out the nook where two newlyweds spent their honeymoon as part of a TV stunt, and the tour concludes with a tape of Kate Smith warbling "God Bless America" while an American flag is projected onto a particularly majestic cave wall. Such theatrics aside, Meramec is gorgeous, with lots of the small, hollow stalactites known as soda straws.

Elsewhere in Missouri, Fantastic Caverns (4872 N. Farm Rd. 125, Springfield; 417-833-2010; fantasticcaverns.com), which once housed a speakeasy and later a weekly radio hootenanny, is America's only ride-through cave. Visitors sit in a Jeep-drawn tram. And Bridal Cave (526 Bridal Cave Rd., Camdenton; 573-346-2676; bridalcave.com), as its name suggests, supplements its tour business by hosting weddings--nearly 2,000 of them since 1949, all immortalized in photo albums in the visitors' center. If you want to be next, nuptial packages start at $400.

Subterranean superhighway

While these sites are all private businesses, some show caves are municipally or even federally operated, most notably Mammoth Cave National Park (Exit 53 off I-65, Mammoth Cave, Ky.; 270-758-2180; nps.gov/maca), which at 360 miles is the world's longest recorded cave system. Mammoth lacks mom-and-pop appeal, but it has other advantages. For starters, your guide will be a knowledgeable ranger instead of a minimum-wage teenager. And while the commercial sites generally offer a single hour-long tour, Mammoth has numerous tour options, including a lantern-lit outing that simulates 19th-century conditions and a six-hour excursion for serious cavers (the staff is happy to discuss which tour is best for you). Moreover, Mammoth's 52,000 topside acres offer activities like camping, fishing, boating and hiking.

Not far from Mammoth is the American Cave Museum (119 E. Main St., Horse Cave, Ky.; 270-786-1466; cavern.org), a small but informative facility that's also the gateway to Hidden River Cave, which you enter by descending through a grand, amphitheater-like sinkhole. Once a dumping spot for trash, the cave has now been cleaned up so successfully that it supports its own little ecosystem--I saw half a dozen crayfish during my recent visit. Also nearby is Lost River Cave, which once housed a nightclub, as well as Diamond Caverns and Onyx Cave and...

Well, you get the idea. The caves I've singled out here are just the tip of the iceberg. If you enjoy one, you may find yourself getting caught up in seeing lots of them. Just remember to let your kids have lunch first.