18 of Earth's most otherworldly and unique caves

Caves have been home to some of the most fascinating legends in modern history.

From the cavernous version of hell in Dante's "Inferno" to epic kingdoms underneath mountains in J.R.R Tolkien's "Lord of the Rings" series, fictional battles throughout history have taken place in dark, gaping crevasses of earth.

Researchers speculate that a giant cavern discovered in southern Greece in 1958 helped serve as the inspiration for the mythical ancient Greek underworld Hades. And although pundits are reluctant to place the island Odysseus was shipwrecked on in Homer's "Odyssey," Croatian locals say the hero swam to a cave on Mijet Island near Dubrovnik.

Don't be surprised if some recent cave discoveries start to influence fiction, as well.

It was only in 2006 that researchers found 'Cueva del Fantasma' -- Spanish for 'Cave of the Ghost' -- a collapsed gorge hidden within the jungles of Venezuela that is big enough to fly helicopter through it unscathed. There is even a picture-perfect waterfall thundering down the cave's mouth.

Three years later, a group of explorers were finally able to propel 80 meters down into the Hang Don Doong cave in Vietnam, a hidden space so big that it could fit a Manhattan city block complete with 40-story skyscrapers.

You don't have to plunge into a dense jungle to stumble across some of the world's most interesting caves. Located in central Slovakia, the Ochtinska cave is a UNESCO World Heritage Site filled with peculiar tufts and spikes of aragonite like a natural Chihuly sculpture. Pop over to neighboring Austria and you will find the world's largest ice cave just outside of Salzburg.

Click through the gallery below to see some of the most unique caves in the world and start feeling like you might even be able to explore like Indiana Jones.