It takes a special type of traveler to leave the comforts of the surface of the planet to spelunk deep into claustrophobic caves. If you're that type of person, this list of 20 unique caves in the world is for you!
All around the world, there are massive caves that stretch for hundreds of miles. Some of these caves are tourist attractions, like the Glowworm Caves in New Zealand. Some caves are even hotels, such as the Grand Canyon Cave Hotel in Arizona. If you're the spelunking type, these caves probably are not for you.
Instead, you'll want to head out to something a little more challenging, a little more terrifying. There are caves so huge that they can fit a 40-story skyscraper inside them. Some of the world's most challenging caves are underwater, making them mysterious and extremely dangerous. You can explore caves of pure ice in the Alps or cave systems that extend more than three hundred miles in Europe!
Some caves are completely closed to the public, such as the Crystal Caves in Mexico, where temperatures reach 150o F (65.5o C) and humidity is at 100%. The Shaft Sinkhole in Australia is so deep that nobody has been able to explore its depths, while the Devil's Hole in Niagara, NY creates small tsunamis and is said to be haunted.
The following are twenty unique caves that the general public would be better off avoiding. If you're among the brave and reckless adventurers who need something more on their travels, then be sure to visit some of these caves!
20 Eisriesenwelt Cave, Austria
Deep in the Austrian Alps, at the base of a plateau among the Alpine Massifs, rests the Eisriesenwelt Cave ("World of Ice Giants" Cave). The cave requires a torturous trek up a mountain or, if you want to forego that, you can take the handy cable car that was installed in 1955. Once inside you'll find a 42 km (26 miles) cave system filled with massive ice towers, both from the ground and the ceiling.
The cave is breathtakingly beautiful, even with its below-zero temperatures, icy floors, and treacherous heights. You'll want to wear warm clothes, and you'll definitely want something bigger than a smartphone to capture photos.
19 Orda Cave, Russia
In the Ural Mountains, near the Russian city of Perm, lies one of the longest underwater caves in the world. Orda Cave stretches for over 3 miles, most of it submerged in water made crystal-clear by the rich gypsum rock of the mountains. With tunnels and shafts descending to nearly 100 feet below the surface, and water temperatures reaching –9o F (-23oC), Orda is not for amateur divers.
To add to the uniqueness of the cave, Russian regulations require that divers use specialized gear to divert the bubbles they make away from the walls and towards the mouth of the cave in order to protect the sensitive gypsum walls.
18 Puerto Princesa Subterranean River, the Philippines
This meandering underground river system is also known as the Saint Paul Underground River, as it travels through the St Paul Mountains on the island of Palawan in the Philippines. It was made a national park in 1992 and then a UNESCO World Heritage Site in 1999, and in 2012 it was named as one of 7 Natural Wonders of the World!
Entering the cave requires a boat, and the 15-mile (24 km) long river empties right out into the sea. The ocean heavily influences the water in the cave, and calm rivers can turn into rising tides and crashing waves real fast!
17 Krubera Cave, Georgia
The world's deepest cave is located near Abkhazia in the Caucasus Mountains. Spelunkers and divers have managed to explore the cave up to a depth of 2,091 meters (1.3 miles) and still, nobody has found the end of it! The cave also travels for 16 km under the mountains, with a dizzying array of side tunnels and winding shafts that can get any foolhardy explorer lost.
Many of the branch tunnels are filled with water. These sumps require professional divers because they go on seemingly forever. Only professional spelunkers and divers should attempt this system. Krubera is not for the faint of heart!
16 Son Doong Cave, Vietnam
Son Doong is the world's largest cave. There really is nothing like it. Entire ecosystems exist inside this cave, from grasslands to jungles to smaller mountain ranges with their own caves! The main cave of Son Doong is three miles long and over 700 feet high and has its own beach complete with tides. The cave system travels for 9 km (6 miles) and contains different chambers of enormous sizes.
Hang Son Doong, as it's officially called, was discovered in 1991 and was made a national park by the Vietnamese government. It takes an expert to navigate the cave as some of the cliffs drop as far as 500 ft!
15 Mammoth Cave, Kentucky
If you want to really get lost in a massive cave system, then head to Mammoth Cave National Park in Kentucky, USA and visit the world's longest cave system. Mammoth Cave travels a mind-boggling 405 miles (652 km) underground, under mountains, under rivers and pretty much under everything else, too.
Mammoth Cave is so vast that parts of it have never been explored, with hundreds of side caves going off in different directions. The cave is also home to five different species of bats, including a bat species thought to have died out with the dinosaurs, so if you don't mind bats, this is the cave for you!
14 Optymistychna Cave, Ukraine
This narrow, claustrophobic gypsum cave in central Ukraine is the fifth longest in the world, reaching 230 km (140 miles) in length. Most of the passageways are less than 5 feet (1.5 meters) in height, although there are a couple of chambers with ceilings up to 33 feet (10 meters) tall.
The gypsum is extremely fragile and hitting the wall too hard could result in a mini cave-in. In some places, the walls are only 30 cm thick! This cave has numerous side-tunnels which branch off the main shaft and turn into mazes of narrow passageways, making Optymistychna one of the most claustrophobic caves on this list!
13 Wind Cave, South Dakota
At 140 miles in length (226 km), and covering multiple levels, Wind Cave is considered the densest maze cave in the world. It's also the first cave in the world to be made into a national park. Wind Cave gets its name from the air that is constantly blowing out of the entrance, caused by differences in air pressure inside and outside the cave.
Don't let the cool air fool you; Wind Cave is a dangerous place to go wandering around in. People get lost in here all the time and the US National Park Service has a special team of spelunkers ready to rescue lost explorers!
12 Cenote Esqueleto, Mexico
More popularly known as the "Temple of Doom", Cenote is a massive underwater cave complex in Mexico that has been featured in films and documentaries. There is a massive 30-foot jump into the water in order to get into the cave. Then the huge cave goes on and on underground, without light, making it extremely dangerous.
The Temple is so dangerous, in fact, that it claims the lives of three people every year, on average. Most divers are content to hang around the sunlit areas and avoid the tight, dark passageways that go on for who knows how long.
11 The Shaft, Australia
This natural sinkhole appears as a tiny hole in a grassy field, but those unlucky enough to fall into it find themselves deep underground in a submerged cave system that is rated as the most dangerous cave dive in the world. The shaft entrance is so narrow that diving equipment has to be lowered down after the diver has gone in. There are hundreds of twisting and turning passageways down there, and fatalities are recorded every year.
There is no natural light in this cave system, and the tunnels are so long and cramped that diver's lights are barely sufficient. Only the bravest should ever attempt this cave.
10 Sima de la Cormisa, Spain
The world's second deepest cave sits right next to two other deepest caves in the world, so if you're really foolhardy there's enough spelunking here to last you a long time! Sima de la Cormisa sits in the Picos de Europa (Peaks of Europe) mountain range, and the cave pretty much drops straight down the middle of a mountain. At 1887 meters in depth (4944 feet), this cave is terrifying!
Terror doesn't stop small groups of adventurous climbers from attempting to scale the cave, however. If you're one of those people who knows what they're doing in caves and on mountains, then this may be right up your alley!
9 Sarma, Georgia
The third deepest cave in the world is another in Georgia. In the western Caucasus mountains, Sarma has been measured at 1800 meters in depth. Unlike Sima de la Cormisa, Sarma is a massive bell-shaped cavern underneath a small mountain. The cavern gets natural sunlight through a gigantic hole, and an ecosystem exists deep at the bottom.
There is crystalline blue water and a small beach in there, although the water is too full of minerals to be potable and it's way too cold for swimming. Nevertheless, expeditions into the cave have been able to set up entire campsites in this massive cave!
8 Krubera-Voronja Cave, Georgia
The deepest cave in the world is another one in the Caucasus Mountains in Georgia. It is the only cave known to be greater than 2 km in depth, and the complex of subterranean passages, caves, and cathedral-sized vaults it feeds are impressive. Krubera is also one of the oldest known caves in the world, predating the Jurassic period and geologists believe it was carved out by prehistoric flooding.
At 2,197 meters in depth, it is easy to get lost here and only professional expeditions are permitted to enter the cave. If you're a pro spelunker, make sure to join one of the scientific teams that come here every year!
7 Yucatan Cenotes, Mexico
Fed by a massive underground river system that flows beneath the entire Yucatan Peninsula, the Yucatan Cenotes isn't just one cave, but a series of beautiful sinkholes that have become popular destinations for eco-tourists. Unlike some of the other caves on this list, the Cenotes of the Yucatan are not dangerous. They are filled with cool water and surrounded by lush tropical flora.
Don't let their Garden of Eden image fool you, however. Most of them require either a bone-rattling climb down sheer rock faces or a 20-foot jump. However you choose to get down to the water, you will be among an adventurous few who have done it!
6 Blue Caves, Greece
These beautiful caves on the west coast of Zakynthos Island offer travelers a beautiful and serene sight. While accessible only by boat, there are plenty around that can be rented and you can spend an afternoon meandering through the dozens of passageways and caverns, all lit up by the brilliant blue waters of the Adriatic Sea.
Make sure you watch the time, however, and heed the advice of the dockmasters. When they tell you to be out of the caves before high-tide, they mean it. One place you don't want to be stuck when the tides come in, or a storm surge hits, is within a coastal cave system!
5 Crystal Cave, Mexico
Discovered in 2000 by miners working on a new tunnel, the Crystal Cave is in Chihuahua, Mexico and is 120 meters (390 feet) below ground. The workers stumbled upon a fascinating scientific find: massive 12-meter tall crystals in a cavern with extreme heat and 100% humidity. The mining operation was called off and scientists called in.
The crystals are the largest in the world, but even more fascinating is the bacteria that scientists were able to recover from them. These organisms do not exist anywhere on Earth's genetic database, making them a completely new form of life! Since then three new chambers have been discovered.
4 Caves of the Thousand Buddhas, China
All the caves on this list were carved out by nature, except one. The Caves of the Thousand Buddhas, near Dunhuang, was carved out of cliffs by Buddhist Monks between the fourth and eleventh centuries. There are 492 caves discovered so far, and many of them travel deep within the rock up to depths of 500 meters or more! All of them are filled with impressive statues of Buddha and elaborate carvings all over the walls.
These caves also house the largest collection of Buddhist art anywhere in the world, so if you're up for several days of wandering around an ancient man-made labyrinth, head to China!
3 Glowworm Caves, New Zealand
There are no other caves in the world like the Glowworm Caves in Waitomo, New Zealand. Here millions of bioluminescent worms hang from the walls and ceilings, creating a fascinating glowing-blue light throughout the cave system.
The worms glow to attract insects, and the sticky silk lines they dangle from catch their prey. There are 300 caves in this system, all filled with millions of the strange blue worms. You won't have to worry about being caught by worms, however, because the tours are all via boat on gently flowing underground water, so enjoy the view high up above you!
2 Skaftafell Ice Caves, Iceland
These awe-inspiring ice caves are the result of a melting glacier high up above it in Skaftafell National Park. The water runs off through crevasses in the ice and, as it travels over smooth, cold ice, the water freezes, creating a new layer of ice. This layering of ice creates new passageways, shifts tunnels into different directions, and creates amazing walls of crystal-clear ice that you need to see to believe.
There are tours through some parts of the ice caves, but much of the complex is closed off to the public for both safety and environmental concerns.
1 Marble Caves, Chile
Partially submerged in Carrera Lake in central Chile lays the most beautiful caves in the world. The Marble Caves have been created by more than 6,000 years of water gently lapping at the marble shores. Inside you will find the blue waters reflected off incredibly smooth marble polished to a sheen by nature. These caves are absolutely incredible and there is nothing else like them in the world.
There are plans to surround the lake with five major dams, which will undoubtedly affect the caves, so if you want to see this natural wonder you need to think about doing it before it's gone.