9 jaw-dropping caves

From: http://www.mnn.com/

CREDIT: ZUMA Press

A spelunker's dream

Humans have discovered and stepped on almost every swath of terrain on the planet, yet there are still places that have not been explored. Modern spelunking expeditions are unlikely to produce such fantastical results as Jules Verne's "A Journey to the Center of the Earth", but there are still some stunning sights to behold. Here are nine amazing caves from around the world that will make your jaw drop. (Text: Caitie Leary/MNN)

CREDIT: Courtesy of Carsten Peter/National Geographic

Cave of the Crystals

The discovery of the Cave of the Crystals in 2000 by miners working 1,000 feet underground proved that there are still astounding natural wonders that humans have yet to stumble upon. Located in the Naica Mine near Chihuahua, Mexico, the cave features enormous crystalline blocks and beams jutting out from all directions. The selenite crystals — some of the largest ever found — formed when the cave, situated along an ancient fault, filled with hot, mineral-rich water. The water remained in the cave for about 500,000 years, providing an ideal climate for the giant crystals to grow.

CREDIT: wanderingz/Flickr

Fingal's Cave

Fingal's Cave, a sea cave located on the uninhabitated island of Staffa, Scotland, consists of a large series of hexagonally shaped basalt columns. It was named after the hero of an 18th century Scottish epic poem by James Macpherson. Because of its arched ceiling, it produces eerie echoing sounds, which prompts its name, "Uamh-Binn," which means "cave of melody" in Gaelic.

CREDIT: Inspiration Point Studio/Flickr

The Eisriesenwelt

About 40 kilometers south of Salzburg, Austria, in the market town of Werfen, lies the largest ice cave in the world. It's called Eisriesenwelt, which means "World of the Ice Giants" in German. It was first explored in 1879 by scientist Anton Posselt. Long before he arrived, locals knew about the cave and believing it was the entrance to hell — and they avoided it. The cave extends 42 kilometers, though only the first kilometer or so is covered in ice, which was formed when snow from outside the cave melted, drained in the cave and froze again during winter. Today the Eisriesenwelt is a popular tourist destination, with about 200,000 visitors every year.

CREDIT: Dave Bunnell

Mammoth Cave

As the longest known cave system in the world, it’s no wonder Mammoth Cave was established as a national park. The Kentucky cave has 367 miles of passageways, and it’s widely believed that many more miles have yet to be discovered. The cave's name originates from it's vast length, as opposed to the popular (yet false) belief that it has something to do with the now-extinct woolly mammoth.

CREDIT: ZUMA Press

Blue Grotto

This famous sea cave is located off the coast of the island of Capri, Italy. It is notable for its gorgeous and brilliantly blue waters, a color created by sunlight shining through the seawater into the underwater passageway. During the times of the Romans, the cave was thought to be the home of witches and monsters, but that doesn't deter visitors today — it remains one of the most popular attractions on the island of Capri.

CREDIT: Stubb/Wikimedia

Cave of the Swallows

First documented in December 1966, the Cave of the Swallows is a pit cave located in San Luis Potosí, Mexico, that plunges more than 1,400 feet down. It attracts many tourists, especially BASE jumpers and vertical cavers. The cave gets its name from the large number of birds — mainly white-collared swifts and green parakeets — that live within the walls of the cave.

CREDIT: ZUMA Press

Dongzhong Cave

Even though its name means "in cave" in Chinese, Dongzhong is both a cave and a school. Opened in 1984 in Ziyun County in China's Guizhou Province, this natural, air hangar-sized cave serves as an educational institution for 186 students and their eight teachers. The cave was carved out from wind, water and other natural forces over the course of thousands of years. It now features small buildings, rooms and sport and recreational areas.

CREDIT: Wikimedia/GNU/CC license

Carlsbad Caverns

Discovered in the late 1890s by cowboy Jim White, Carlsbad Caverns is located near the Guadalupe Mountains of southeastern New Mexico and boasts the third largest cave chamber in the Americas. The park features a vast array of rooms and chambers: the Big Room, the New Mexico Room, King's Palace, Queen's Chamber, the Spirit World and more than 100 others. It was officially established as a national park in 1930, and since then, it has welcomed 400,000 visitors a year.

CREDIT: Yam Bare Munch/Flickr

Waitomo Glowworm Cave

The Waitomo Glowworm Cave is located in the Waikato region of New Zealand's North Island. It is part of the Waitomo Caves system, which includes Ruakuri Cave and Aranui Cave. As the name suggests, the cave serves as the home to glowworms, specifically Arachnocampa luminosa, which are a type of fungus gnat species that glow in their larval stage. Because it was underwater 30 million years ago, the cave is made from limestone composed of fossilized shells, skeletons and coral.