54 Best Sights in USA

While Indigenous people were the first to explore and use the caves, rancher and miner Absalom Lehman is credited with discovering this underground wonder in 1885. The single limestone and marble cavern is 2½ miles long and looks as if it’s covered in melting wax frozen in stony time. Geology fans will identify stalactites, stalagmites, helictites, flowstone, popcorn, and other bizarre mineral formations that cover almost every surface. Lehman Caves is one of the best places to see rare shield formations, created when calcite-rich water is forced from tiny cracks in a cave wall, ceiling, or floor. Year-round the cave maintains a constant, damp temperature of 50°F, so wear a light jacket and nonskid shoes. Go for the full 90-minute tour if you have time; during summer, it's offered several times a day, as is the 60-minute tour. Expect daily tours during the winter. Children under age 5 are not allowed on the 90-minute tours, except during the winter; those under 16 must be accompanied by an adult. Take the 0.3-mile Mountain View Nature Trail beforehand to see the original cave entrance and Rhodes Cabin, where black-and-white photographs of the park's earlier days line the walls.

Tickets are extremely competitive and available up to 30 days in advance at www.recreation.gov. Day-of tickets are sometimes available but never guaranteed.

A relatively level (it has some steps and a short section that's a bit steep), paved pathway leads through these almost hallucinatory wonders of various formations and decorations. Exhibits and signage also provide a layman's lesson on how the cavern was carved (for even more details, rent an audio guide from the visitor center for $5).

Discovered by two boys in 1880, the cave has been exploited as a tourist sensation ever since. The only way to enter the site is by purchasing a tour, but once inside the cave you'll forget the hype and commercialism of the gimmicky entrance. The cave contains examples of every major sort of limestone formation, from icicle-shaped stalactites and stump-like stalagmites to delicate anthodite crystals (or cave flowers), flowstone (or frozen waterfalls), and cave popcorn. Enthusiastic guides host easy 45-minute walking tours, adventurous cave expeditions, and lantern tours that last 1½ hours. An outdoor ropes course and rides like the Terror-dactyl, which swings riders off a 200-foot cliff, offer more fun outside of the cave.

That's not a typo; this cave officially has no name—or rather, not having a name is part of its name. The story goes that in 1939, the owner of the cave, James Horne, held a public contest to name the cave. A young boy commented that the geological site was too beautiful to name and won the contest with the suggestion that it be called Cave Without a Name. Similar to the other living limestone caverns in the region, the cave has magnificent stalactite and stalagmite formations and calcite deposits. Be sure to make reservations in advance.

One of more than 200 caves in Sequoia and Kings Canyon, Crystal Cave is composed largely of marble, the result of limestone being hardened under heat and pressure. It contains several eye-popping formations. There used to be more, but some were damaged or obliterated by early-20th-century dynamite blasting. You can see the cave only on a tour. The Daily Tour ($17), a great overview, takes about 50 minutes. To immerse yourself in the cave experience—at times you'll be crawling on your belly—book the exhilarating Wild Cave Tour ($140). Availability is limited—reserve tickets at least 48 hours in advance at or stop by either the Foothills or Lodgepole visitor center first thing in the morning to try to nab a same-day ticket; they're not sold at the cave itself. 

If you're interested in spelunking, take the time to explore Kaeleku Caverns (aka Hana Lava Tube), just after mile marker 31 and a mile down Ulaino Road. The friendly folks at the cave give a brief orientation and promptly send you into Maui's largest lava tube, accented by colorful, otherworldly formations and a lot of fascinating history. You can take a self-guided, 30- to 40-minute tour daily 10:30 am until 4 pm. LED flashlights are provided, and close-toed shoes are recommended. For those who don’t want to explore the caverns, this still makes for a great stop to check out the world’s only red ti leaf maze on the grounds.

The publicity that surrounded the official opening of Kartchner Caverns in 1999 was in marked contrast to the secrecy that shrouded their discovery 25 years earlier and concealed their existence for 14 years. The two young spelunkers, Gary Tenen and Randy Tufts, who stumbled into what is now considered one of the most spectacular cave systems anywhere, played a fundamental role in its protection and eventual development. Great precautions have been taken to protect the wet-cave system—which comprises 13,000 feet of passages and two chambers as long as football fields—from damage by light and dryness.

The Discovery Center introduces visitors to the cave and its formations, and guided Rotunda/Throne Room tours take small groups into the upper cave. Spectacular formations include the longest soda straw stalactite in the United States at 21 feet and 2 inches. The Big Room is viewed on a separate tour for ages seven and up: it holds the world's most extensive formation of brushite moonmilk, the first reported occurrence of turnip shields, and the first noted occurrence of birdsnest needle formations. Other funky and fabulous formations include brilliant red flowstone, rippling multihued stalactites, delicate white helictites, translucent orange bacon, and expansive mudflats. It's also the nursery roost for female cave myotis bats from mid-April through mid-October, during which time this lower cave is closed.

The total cavern size is 2.4 miles long, but the explored areas cover only 1,600 feet by 1,100 feet. The average relative humidity inside is 99%, so visitors are often graced with "cave kisses," water droplets from above. Because the climate outside the caves is so dry, it is estimated that if air got inside, it could deplete the moisture in only a few days, halting the growth of the speleothems that decorate its walls. To prevent this, there are 22 environmental monitoring stations that measure air and soil temperature, relative humidity, evaporation rates, air trace gases, and airflow inside the caverns.

Tour reservations are strongly recommended, especially during winter months. If you're here and didn't make a reservation, go ahead and check: sometimes same-day reservations are available (call or arrive early in the day for these).

Hiking trails, picnic areas, and campsites are available on the park's 550 acres, and the Cave Café, open daily, serves pizza, hot dogs, salads, and sandwiches.

This way-out adventure explores the underbelly of the world's most active volcano via the Kazamura Lava Tube system. The world's longest lava tube system—more than 40 miles long, with sections up to 80 feet wide and 80 feet tall—is 500 to 700 years old and filled with bizarre lava formations and mind-blowing colors. Tours, customized to groups' interests and skill levels, focus on conservation and education and take visitors through beautiful lava caves unlike any others in the world. The tours are by reservation only and are well worth the extra detour (about 40 minutes off the main highway) and planning. Equipment is included. When you make your reservation, you will be given detailed directions to the location.

Stalagmites, stalactites, flowstone deposits, and crystals entice visitors to the Lake Shasta Caverns. To see this impressive spectacle, you must take the two-hour tour, which includes a catamaran ride across the McCloud arm of Lake Shasta and a bus ride up North Grey Rocks Mountain to the cavern entrance. The temperature in the caverns is 58°F year-round, making them a cool retreat on a hot summer day. The most awe-inspiring of the limestone rock formations is the glistening Cathedral Room, which appears to be gilded.  In summer, it's wise to purchase tickets online a day or more ahead of your visit.

Formed over thousands of years from water cutting and dissolving limestone bedrock, Longhorn Caverns are a fantastic exhibit of Texas natural history. With a history of Comanche tribes seeking refuge in the caves and calcite-crystal beds, the caverns are a perfect destination for families interested in how the limestone caverns in the Hill Country were formed. Be sure to wear rubber-soled shoes; it gets slippery down there.

For different sorts of underground jewels, wander into an ancient limestone cave, where stalactites and stalagmites, not gold and silver, await. Take the 235-step Spiral Tour down a staircase built in 1922 into the vast main cavern, or descend farther on the Expedition Tour caving adventure. It's best to make a reservation here.

As natural daylight recedes, a self-guided, paved trail twists and turns downward from the yawning mouth of the main cavern, about 100 yards east of the visitor center. The route is winding and sometimes slick from water seepage aboveground. A steep descent of about 750 feet, much of it secured by hand rails, takes you about a mile through the main corridor and past dramatic features such as the Bat Cave and the Boneyard. (Despite its eerie name, the formations here don't look much like femurs and fibulae; they're more like spongy bone insides.) Iceberg Rock is a massive boulder that dropped from the cave ceiling millennia ago. After about a mile, you'll link up underground with the Big Room Trail and can return to the surface via elevator or by hiking back out (starting your ascent no later than 2:30). Footware with a good grip is recommended.

Marble caves, large calcite formations, and huge underground rooms shape this rare adventure in geology. Guided cave tours take place late March through early November. The 90-minute ½-mile tour is moderately strenuous, with low passageways, twisting turns, and more than 500 stairs; children must be at least 42 inches tall to participate. Cave tours aren't given in winter. Aboveground, the surrounding valley holds an old-growth forest with some of the state's largest trees, and offers some excellent and generally uncrowded hiking.

GPS coordinates for the caves often direct drivers onto a mostly unpaved forest service road meant for four-wheel-drive vehicles. Instead, follow well-signed Highway 46 off U.S. 199 at Cave Junction, which is also narrow and twisting in parts; RVs or trailers more than 32 feet long are not advised.

More than 80 years ago, Leo Lambert and a small crew spent 17 hours inside this cavern before discovering what is now the world's tallest and deepest underground waterfall (145 feet) open to the public. Guided tours begin every few minutes. After your visit underground, head up the 70-foot-high Lookout Mountain tower for a spectacular panorama of the Tennessee River Valley, either with your own peepers or by using one of the coin-operated telescopes. Younger children can romp on the Fun Forest Playground or pan for gems. For an adult adrenaline rush, the ZIPstream experience is a suspended obstacle course, culminating in 700 feet of round-trip zip-lining with fabulous views of Chattanooga.

The temperature inside the cave is 60°F, so bring a light sweater or jacket.

Known to Native Americans for centuries, Wind Cave was named for the strong air currents that alternately blow in and out of its entrances. The cave’s winds are related to the difference in atmospheric pressure between the cave and the surface. When the atmospheric pressure is higher outside than inside, the air blows in, and vice versa. With more than 160 miles of known passageways divided into three different levels, Wind Cave ranks among the longest in the world. It’s host to an incredibly diverse collection of geologic formations, including more boxwork than any other known cave, plus a series of underground lakes, though they are located in the deepest parts of the cave not seen on any tours. All tours are led by National Park Service rangers and leave from the visitor center. These tours allow you to see the unusual and beautiful formations with names such as boxwork, cave popcorn, and frostwork. The cave remains a steady 54ºF year-round, so wear closed-toe shoes and bring a jacket or sweater. Tickets are sold at the visitor center and sometimes sell out more than an hour before each tour during summer, so plan accordingly. Check out the park website for the different tours, times, and pricing.

In the amphitheater at the Natural Entrance (off a short trail from the main parking lot) a ranger discusses the park's batty residents before the creatures begin their sundown exodus. The bats aren't on any predictable schedule, so times are a little iffy. Ideally, viewers will first hear the bats preparing to exit, followed by a vortex of black specks swirling out of the cave mouth in search of dinner against the darkening sky. When conditions are favorable, hundreds of thousands of bats will soar off over the span of half an hour or longer.

Measuring nearly 2½ miles in mapped length, Ape Cave is the longest continuous lava tube in the continental United States. Two routes traverse the tube: the lower route is an easy hour-long hike, while the upper route is more challenging and takes about three hours. Bring at least two light sources (you can rent lanterns from the headquarters for $5) and warm clothing. In high season ranger-led walks are sometimes available; inquire at the Ape's Headquarters, off Forest Service Road 8303, 3 miles north of the junction of Forest Roads 83 and 90. Timed reservations are needed and can be booked at  www.reservation.gov for a $2 fee; a Northwest Forest Pass ($5 daily) is required for parking. The gate to Ape Cave is closed November through mid-May, though the cave can be reached by a half-mile trail from Trail of Two Forests Sno-Park off-season ($25 parking pass required).

The 400,000-member Brazilian free-tailed bat colony here snatches up 3 tons of bugs a night. Watch them leave at dusk from the park amphitheater at the Natural Entrance, where a ranger discusses these intriguing creatures. The bats aren't on any predictable schedule, so times can vary. Ideally, viewers will first hear the bats preparing to exit, followed by a vortex of black specks swirling out of the cave mouth in search of dinner against the darkening sky. When conditions are favorable, hundreds of thousands of bats will soar off over the span of half an hour or longer.

Guided 45-minute tours take you past stalactites, stalagmites, and rare formations of delicate helictites in three underground chambers, one of which also contains a lake. Black Chasm isn't the largest cave in the Gold Country, but its crystals dazzle both eye and camera—the Landmark Chamber, the tour's third stop, inspired a scene in the 2003 film The Matrix Reloaded. Outside is an area where kids can "pan" for crystals.  The same outfit also conducts tours of California Cavern State Historic Landmark, 32 miles south of Volcano, though the days open are less regular.

Amethysts, logomites, calcite crystals, and other specimens fill this 60-million-year-old, privately owned cave, formed slowly by water trickling through limestone rock and first documented by gold seekers in 1882. Half-hour and hour-long walking tours, as well as gemstone and fossil mining, are available. Tours depart approximately every 20 minutes.

The Kings River has carved out hundreds of caverns, including Boyden, which brims with stalagmite, stalactite, drapery, flowstone, and other formations. In summer, the Bat Grotto shelters a slew of bats. If you can't make it to Crystal Cave in Sequoia, Boyden is a reasonable substitute. Regular tours take about 45 minutes and start with a steep walk uphill.

Take a one-hour tour here past awe-inspiring limestone formations, deep caverns, stalactites, and stalagmites; you may even catch a glimpse of the endangered Cascade Caverns salamander. Watch for the impressive 100-foot waterfall spilling into a black pool at the end of the tour. Wear rubber-soled shoes; the caverns are wet and can get slippery.

This limestone grotto 20 miles southeast of Tucson is the largest dry cavern in the world. Guides discuss the fascinating crystal formations and relate the many romantic tales surrounding the cave, including the legend that an enormous sum of money stolen in a stagecoach robbery is hidden here.

Forty-five-minute cave tours begin every hour on the hour and require a ½-mile walk and a climb of 363 steps. The park includes a ranch area with horseback rides through saguaro forests offered October–May (from $40), a gemstone-sluicing area, a petting zoo, a gift shop, and a café. You can also picnic, hike, and mountain-bike in the surrounding 2,400-acre wilderness park; campsites ($10) are on a first-come first-served basis.

Formed from limestone millions of years ago, these caves have been a popular local attraction since they were discovered in the mid-19th century. Descend into this series of subterranean galleries, and you'll get up close to enormous stalactites and stalagmites, projecting onyx peaks, and rock palaces. Temperatures in the cave hover around 58°F throughout the year. Visits are by hour-long guided tour.

A relic of Mammoth Cave's geologic younger years, Dixon Cave Entrance lies at the end of an underground passage once connected to the rest of the cave. Now choked with stone, this dry hillside pit was at one time a mighty spring that fed Green River. Now, standing on the overlook just off Dixon Cave Trail, you peer down into darkness as though backward into time itself.

One of the largest Mexican free-tailed bat colonies in the world is found in the hills of Mason County. Managed by the Texas Nature Conservancy, Eckert James River Bat Cave, a maternity bat cave, is home to more than 4 million. Only females inhabit the cave, where they bear and rear their young each spring; they depart in mid-October. You can watch in the evening and morning as the entrance to the cave swarms with female bats leaving and returning from an evening hunt to feed their pups. Stand clear of the entrance unless you don't mind bat guano or having thousands of female bats buzz by. The best way to glimpse this phenomenon is from a safe distance a few hundred yards away.

The best known of the large natural caverns that pockmark northern Prince of Wales Island has one of the deepest pits in the United States. Paleontologists have found a wealth of black bear, brown bear, and other mammal fossils in the cave's 13,000 feet of passageways, including some that date back more than 12,000 years. The Forest Service leads free, two-hour tours of El Capitan Cave several times a week in summer. It takes some work to get to the cave's mouth, but if you're up for a 1,100-foot hike up a 367-step stairway, it's well worth the effort. The rangers pause along the way to give visitors time to catch their breath. Reservations are required at least two days ahead, and no children under age seven are permitted. Bring a flashlight and wear hiking or rubber boots. A light jacket is also helpful, as the cave gets quite cool.

You won't want to miss the cave tours revealing stalactites, stalagmites, soda straws, columns, rim stones, flowstones, and "waterfalls" of solid rock at these underground caverns, where the temperature hovers at an oh-so-pleasant 68°F year-round. The park includes a visitor center with museum exhibits and a video in addition to picnic pavilions, campsites, a small playground, and a ½-mile loop trail. Tours can be booked in advance online ( www.floridacavernsgiftshop.com).

A beautiful and surreal crystal-clear stream runs through this underworld of grottoes and natural chimneys. This cave was a source of flint for Native American arrowheads and later served as a clandestine site for moonshine production. A stereophonic sound system adds to the experience. Pack a jacket even if it's sweltering outside. Temperatures inside the cavern hold steady year-round at 58 degrees.

Glenwood Springs is home to the Historic Fairy Caves (now part of the adventure park), whose subterranean caverns, grottoes, and labyrinths are truly a marvel of nature—the area was touted as the "Eighth Wonder of the World" when it opened to the public in the 1890s. The still-amazing caves are easily accessible year-round via the Glenwood Gondola, which offers a bird's-eye view of downtown, the Colorado River, and surrounding mountains. Choose from two different 40-minute walking tours of the caves, or opt for the crawl-on-your-belly "Wild Tour" spelunking adventure. For a second helping of adrenaline, try the gravity-powered alpine coaster that winds down 3,400 feet down the mountain; sail out over 1,300 feet above Glenwood Canyon on a giant swing; or drop, roll, and twist on the Defiance roller coaster that overhangs a cliff.