These Cool Caves Are the Ultimate Adventure Destinations

Near the border of the German state of Thuringia, the Saalfeld Fairy Grottoes (or Feengrotten) used to be mined for shale and were largely forgotten between the 19th and 20th centuries. In 1910 they were rediscovered, but far from being a derelict old cave system, the Fairy Grottoes had developed stunning multicolored mineral deposits. Today, one of the caverns is illuminated with colorful lights to further enhance the mineral deposits, and the Feenweltchen village above the caves is a family-friendly fantasy experience you won’t want to miss. Top off the day with the interactive museum, the Grottoneum, where you can touch, smell, and even taste different exhibits.

Running for more than nine miles, this is the largest cave in the world. Located in Vietnam and connected to another cave system by its river, there are three ceiling collapses along its length, allowing sunlight to come through and lush vegetation to grow. Sơn Đoòng was created by the river that runs through it, and experts estimate it to be anywhere from two to five million years old. Sơn Đoòng is recommended for intermediate cavers, as its entrance is tricky to traverse. Guided tours are operated exclusively by Oxalis Adventure Tours.

What better adventure than delving into a mystery thousands of years old? Shell Grotto in Margate, Kent is a subterranean passageway lined with intricate murals made entirely of seashells. Discovered in 1835, experts have been unable to make a definitive estimate of its age, and its purpose also remains a total unknown — though some theories suggest it could be related to the Knights Templar, a prehistoric astronomical chamber, or some 18th-century rich guy’s hobby. Whatever the reason for its existence, there’s no denying that Shell Grotto is one of the most fascinating and beautiful subterranean wonders to visit.

In Juneau, Alaska, the Mendenhall Ice Caves meander through the Mendenhall Glacier, blazing blue and white as sun shines through the ancient ice. Travelers describe them as ethereal, breathtaking, awe-inspiring — you get the idea. Because the Mendenhall Glacier is ever-changing, the caves themselves may not be the same from visit to visit, but that just makes the experience that much more unique. There are several Alaskan tour groups that provide guided tours through the Ice Caves and around the surrounding Alaskan landscape. It’s well worth exploring the world around the glacier in addition to within it.

The Waitomo Glowworm Caves are home to a species of glowworm found only in New Zealand, and boasts the largest and brightest population people are able to visit. With a focus on environmentalism and sustainability, local tour companies educate travelers on the importance of preservation while bringing visitors on a blackwater rafting adventure they’ll never forget. If rafting isn’t quite your thing, you can also hike. Stop at the Waitomo Caves Discovery Centre and learn more about the glowworms and New Zealand’s unique fauna, and book tours for all levels.

Capri’s famous sea cave is flooded with stunning blue light, and has a long and storied history including as a Roman marine temple and the personal bathing pool of Emperor Tiberius. Today, though swimming is not allowed, travelers interested in experiencing Blue Grotto for themselves can book a sea tour and be rowed inside. The light is best between noon and 2 p.m., and the Grotto is generally closed during the winter to avoid bad weather. After your trip into the Grotto, you can venture over to the Casa Rossa museum to see the ancient Roman statues that were once displayed inside.

Fingal’s Cave owes its fame to the naturally formed hexagonal basalt columns that surround the entrance. It’s easy to see how it has inspired fantasy landscapes, music, and myths aplenty. Travelers can take a guided tour to hike within the cave and see the Isle of Staffa, on which it is located. Get ready for the ultimate karaoke — Fingal’s Cave is legendary for its incredible natural acoustics.

The special ecosystem within Škocjan Caves, in addition to their breathtaking beauty and massive size, earned them a spot on UNESCO’s list of cultural and natural world heritage sites in 1986. Every year, thousands of people flock to the entrance, where the Reka River is swallowed by the caves. Located in Slovenia, they have been inhabited since the Mesolithic period, and trekking through their chambers feels a bit like going back in time.

Kentucky’s Mammoth Cave National Park is home to several cave systems, but the most popular and famous is Mammoth Cave itself. Called “a grand, gloomy, and peculiar place” by early guide Stephen Bishop, Mammoth Cave lives up to its name, with over 400 miles of cave system to explore. Its history spans over 5,000 years. Several sets of mummified Native American remains have been found there in that time, and it was also a touchstone in the Kentucky Cave Wars and the national park movement. Tours are offered by the National Park Service, and travelers can stay in nearby lodging to have easy access to the entire park.

Barton Creek Cave may seem small compared to its companions on this list, but what it lacks in size it makes up for in story. As a Mayan ceremonial cave, its rich history is as fascinating as its soaring ceilings. Traveling by canoe, adventurers will see 10 ledges that historians have determined were staging areas for Mayan rituals, including fertility rites and human sacrifice. Part of the cave also served as a burial chamber, with the remains of at least 28 humans having been identified. Its fascinating history makes Barton Creek Cave a true contender for must-see natural wonders.

A UNESCO world heritage site, the Puerto-Princesa Underground River in Palawan is over 30 million years old. Described as eerie, spine-tingling, and awe-inspiring, the Underground River is traversable by kayak, allowing you to absorb the experience in serenity. While some of the cave is inaccessible due to lack of oxygen, the first mile is available to everyone and another two and a half are accessible with a special permit. Millenia-old bone fossils are visible in the walls along this special stretch, but the cave’s soaring ceilings — almost 250 feet high — are open for everyone to enjoy. The park surrounding the river is well worth exploring, too, with several species of wildlife that can be found only in Palawan.