A massive volcanic plug is now a protected area that hosts a number of bird species.

A 300-yard long natural tunnel runs through a ridge deep in the Appalachian Mountains.

The water in this preserved area spawns vegetation that gives it a deep green color.

This picturesque cliffside beacon no longer calls to sailors but shines once a year in honor of a famous shipwreck.

This state park was once an important Native American cermonial center.

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

Bad farming practices caused this unnatural natural wonder.

A remote desert lookout offers unparalleled views of the California badlands for those who brave the trek.

Rising out of miles of farmland, these buttes are sometimes called the world's smallest mountain range.

This quiet park's strange sedimentary spires were named after Kodak's color film.

This narrow canyon has been carved by the river over thousands of years into spectacular and curious forms.

Moonbows over Kentucky.

Bizarre lunar-like landscape with thousands of large stone "hoodoos."

One of the world’s largest and deepest freshwater springs, where mastodons once roamed.

Legend has it the mill owner's daughter, Mary Musgrove, helped a Patriot soldier hide behind these falls.

A historic blockhouse and trading post give a glimpse into the early colonial history of South Carolina.

This Florida sinkhole hides a rainforest-like micro-environment in its depths.

This scenic Maryland park was the site of one of the worst prison camps of the Civil War.

An exercise in patience and imagination, where Mother Earth turned common stuff into precious hidden treasures.

The beauty and the beast of hydraulic mining is on full display at this California Historic State Park.

Even Henry David Thoreau found this glacial pothole irresistible.

These huge stone ovens in the desert fueled the Nevada silver boom, and may have also been a hideout for outlaws.

The scant remains of an expansive indigenous civilization can be seen at this Arkansas state park.

The only diamond mine in the world where you can keep what you find.