A true treehouse near Hawai'i Volcanoes National Park.

Hide from the tourist hordes in these relatively unknown, and unguarded lava caves.

These picturesque Hawaiian falls are home to a rare species of fish that uses a special sucker to climb up cliffs.

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

Despite violent work crews and massive delays this abandoned canal tunnel was built to last into the modern day.

These strange large stones served as a campsite and lookout post for generations of Native Americans.

Amazing pre-Civil War ruins alongside a shallow, rocky river that hosts beautiful (but endangered) lilies.

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

A metal tree emits eerie, melodic notes on top of Lancashire's Crown Point.

Friction between grains of sand cause a curious "singing" sound.

This 150 foot seven-tiered cascading waterfall is one of the hidden gems of the White Mountains.

A very big rock just plopped down in the New England woods.

The entire length of the border is marked by a 20-foot-wide slash through the trees.

According to the experts at the Guinness World's Record office, this is the longest candy counter in the world.

Tour the world's largest deep-hole dimension granite quarry, where you can view the plant where gravestones are made and roll a ball down the outdoor granite bowling alley.

Come for the gun-toting hillbilly madman, stay for the ice-cream loving basketball bears.

One of the most scenic falls in Massachusetts has a history of death and grim legend.

This locally-famous crevasse in New York State is icy all year round.

No one really knows how these old hobby horses got here, but the herd keeps growing.

On top of Gibbet Hill lie the ruins of a lavish turn-of-the-century estate that never quite came to be.

The ruins of a Massachusetts prison farm can still be found crumbling the woods of a state park.

One man is on a singular quest to name an island after a famous hip-hop artist.

This railroad tunnel was once the longest in Massachusetts.

The self-proclaimed world's smallest museum, located next to a Massachusetts sandwich chain.