- 1 / 10ScotlandFingal's Cave, Scotland
Geometry lovers will delight in the crazy-cool basalt columns that greet those exploring this Scottish cave. This natural wonder has amazed visitors throughout the ages; in fact, famed German composer Felix Mendelssohn was so taken by its splendor in 1829, that it inspired him to write the "Hebrides" Overture.
Photo by James West
- 2 / 10AlaskaMendenhall Ice Caves, Alaska
Relatively difficult to reach, the glowing-blue Mendenhall ice caves are situated underneath the 13-mile-long glacier of the same name. But this otherworldly sight won’t be around forever—although glacier melt originally formed these caves, rising global temperatures also mean that they will be the cause of its eventual disappearance.
Photo by Samantha Juda
- 3 / 10ItalyBlue Grotto, Capri
This small sea cave on the island of Capri is one of the country’s most famous. Red particles are filtered out of the light that enters into this grotto, giving the water within a fantastical blue glow. Lie flat in a rowboat while an opera-singing local steers you through and experience the wonder for yourself.
Photo by Ellie/Flickr
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- 5 / 10MexicoCave of the Swallows, Aquismon
At first glance this cave might just look like a 200-foot wide hole in the ground, but the entrance to Cave of the Swallows merely hints at the natural wonder that this place holds. The 1,200-foot sheer drop into the Earth not only makes it not only a popular spot for BASE jumpers, but also the second-deepest pit in Mexico. If freefalling to the bottom sounds less than appealing, most travelers visit the spot early at dusk or dawn to witness hundreds of swallows emerge from the cave’s mouth.
Photo by @josh_hydeman
- 6 / 10PortugalBenagil's Sea Cave, Algarve
Get the best of the beach without the fear of a sunburn at this dreamy sea cave on the Algarve coast of Portugal. In addition to the cave’s stunning arch, sunlight that reflects off of its pale walls gives the water a picturesque green glow.
Photo by Daniel Gillaspia/Flickr
- 7 / 10SloveniaPostojnska Cave, Slovenia
There is no shortage of sights to see at the Postojnska cave system in Slovenia. There are, of course, the caves themselves, which are 24 kilometers long and dripping with stalactites and stalagmites at every turn. Visitors can hop aboard the in-cave minitrain, explore by foot, or settle in for a musical performance. Once outside again, you can’t miss Predjama Castle, the largest cave-castle in the world.
Photo by Dominik Gobi
- 8 / 10MalaysiaDeer Cave, Mulu National Park
It has the second largest entryway of any cave in the world, and its facade looks like something out of Avatar. As if that weren’t enough, the interior of the cave is 122 meters high and filled with vegetation, surreal rock formations, and hundreds of thousands of bats. The cave was named after the deer, native to the park, that long ago used its spacious cavern as shelter from the surrounding rain forest.
Photo by Bernard Dupont/Flickr
- 9 / 10VietnamHang Son Doong Cave, Phong Nha Bang Ke National Park
Tall enough to house a 40-story skyscraper and long enough to fit a full New York City block, Hang Son Doong is so spacious that a 747 could comfortably fly through. This cave, located in Phong Nha Ke Bang National Park in central Vietnam, was only discovered in 2009, and is now regarded as the world’s largest. Its size is nearly unbelievable, but even more enchanting is the cave’s very own biosphere, complete with surreal “indoor” clouds and a jungle-system blanketing the floor.
Photo by @studio_tu
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