When we think of exploring different worlds, we usually think of outer space or the depths of the ocean. But what if another world is beneath us, hidden away from plain sight? Caves are a lesser-explored frontier that is worth exploring. No two caves are the same, and they each offer a number of natural wonders to take in. An added perk? The word often used for exploring them is "spelunking," which adds a bit more fun.
If you’re not familiar, spelunking is the traditional way to describe caving, exploring caves through walking, climbing, squeezing, or crawling. The action-packed adventure is guided by nothing more than a headlamp. While spelunkers are sure to get a little dirty, the caves reward the effort with spectacular rock formations, waterfalls, and creatures, among other things. But like anything, some caves are better—and bigger—than others.
From the longest cave in the world in Kentucky to the largest gypsum cave in Ukraine to a three-million-year-old cave in Vietnam, we’ve found the eight largest caves in the world. No need to book that pricey charter to outer space. If you pick one of these caves, you’ll discover a new world on your very own planet.
Mammoth Cave, Kentucky
Located in near Brownsville, Kentucky, Mammoth Cave is the longest cave in the world, measuring 405 miles. Ranger-led tours of the vast caverns are available in durations ranging from one to six hours. The cave is home to a Native American burial site, several species of bat, and a limestone labyrinth.
Optymistychna Cave, Ukraine
The largest gypsum cave in the world, Optymistychna is located near the Ukrainian city of Korolivka, Borshchiv Raion. Considered a natural wonder of Ukraine, the cave is available to be explored. Just be sure to avoid those huge crystals, stalagmites, and stalactites.
Jewel Cave, South Dakota
More than 195 miles of mapped passages make up Jewel Cave, the third largest cave in the world. Jewel Cave is considered a “breathing cave,” where air enters and exits the cave with changes in atmospheric pressure. Located in South Dakota, the cave is near the Black Hills and the Badlands.
Hang Son Doong, Vietnam
This three-million-year-old cave in Vietnam is a rare and relatively undiscovered treasure—more people have summited Mt. Everest than visited the cave. Hang Son Doong, considered to be the largest cave in the world, with dimensions of more than three miles in length and heights of more than 200 meters, can fit an entire New York City block inside its cavern. The cave opened in 2013, and small groups are let in for tours.
Gua Air Jernih, Malaysia
Enter Gua Air Jernih, a Malaysian cave, from the banks of the Long Pala river in Gunung Mulu National Park. The longest cave in Asia, Gua Air Jernih measures more than 189 kilometers and has labyrinths on five levels. The lower levels let in the flow of water the cave is known for.
Sistema Ox Bel Ha, Mexico
This cave system in Quintana Roo, Mexico, boasts the largest explored underwater cave in the world. Its name means “Three Paths of Water.” Among dry caves, it ranks fourth, so no worries if you’re not scuba-certified.
New Athos Cave, Georgia
Located in the nation of Georgia, the New Athos Cave is located inside the Iberian Mountain. A popular tourist destination, the cave can be reached by railway. Much of the cave has yet to be explored, but the largest cavern is more than 800 feet long and 160 feet wide.
Shuanghedong Cave Network, China
Shuanghedong is the longest cave in China located near the town of Wenquan in Suiyang County, Guizhou Province. The cave is home to waterfalls and a number of creatures including shrimp and salamanders. It’s also full of dolomite and gypsum.