Sail through this subterranean show cave that is home to a legend that would go on to name nearly everything around it.

Tubing through a cave lit with glowworms is a magical underground experience.

A cave's rare beauty held a cavernous secret hidden underground.

This Irish show cave is said to have been the site of a Viking massacre that claimed 1,000 lives.

One man has carved a number of natural New Mexico caves into psychedelic sandstone temples.

Amazing taxidermy dioramas from the 1960s in a cement building meant to look like an ice cave.

This natural marble cave is one of only five national monuments in Oregon.

This astonishingly geometric cave has inspired everyone from Jules Verne to Pink Floyd.

River pirates, murderous bandits, and serial killers used this Illinois cave as their debauched hideout.

A tunnel of hardened lava along Maui’s famous Road to Hana.

This popular tourist cave was ignored for almost 200 years before being mined into an attraction.

Cavernous opening completely encased in Karst limestone.

Inhospitable caverns just beneath this island paradise offer insights into alien worlds.

Impressive sink holes fill this untouched old-growth forest in the Bahamas.

Only known mainland rookery of the threatened Stellar sea lion.

This cavernous abandoned marble mine is popular with ice skaters in the winter.

Empty, but not abandoned, this cavernous Brooklyn loading dock was once considered the largest individual building in the world.

The largest known open fault in the United States is basically a giant natural refrigerator.

What was once the largest mine in North America has left behind a hollow hill filled with bright blue waters.

Its dark depths conceal millions of rare, delicate crystal formations.

A cave on the Maryland border where civilians took refuge during the bloodiest battle of the Civil War.

An organ located deep within a cave, whose "pipes" are the geological features of the cave itself.

A soon-to-be-forgotten roadside spectacle loaded with local lore.

A well-preserved network of cavernous tunnels have spent silent centuries removing Toronto's waste.