Shoreline strewn with the remains of ghostly fallen trees.

This long, dark tunnel is open to hikers, but those without lights are known to get confused even on the straight path.

An obscure waterfall that looks like something out of a fantasy novel.

A bike being "eaten" by a tree is the real Vashon legend behind popular children's book, "Red Ranger Came Calling."

A wall of chewing gum moonlights as collective art.

Rustic natural hot springs in the deciduous rain forest.

Stroll through a wonderland of stupendous moss-covered trees.

The longest continuous lava tube in the continental U.S. offers 2.5 miles of dark explorations for the adventurous.

The wreckage of a deadly bomber plane crash can still be found near an Arizona peak.

Walk through the actual strap iron cells and solitary chambers of Arizona Territory’s first prison.

An artificial crater field that trained astronauts for lunar exploration.

This secluded aqua waterfall in the Grand Canyon is the perfect swimming hole, and the Havasupai tribe's fiercely protected natural wonder.

Limestone caves with spectacular showcase chambers.

Eons ago, a rushing lava river formed this pristine passage through solid rock.

An arsenic-filled pool in the Grand Canyon takes on the appearance of a giant, overflowing pumpkin.

This 4,000-foot-diameter hole is touted as "the most well known, best preserved meteorite crater on Earth."

Rippling sand dunes frozen in the Arizona rock.

During prohibition, corrupt city officials ran drinking dens under the streets of Downtown Los Angeles.

The longest continuous lava tube in Oregon.

You might know it as the Overlook Hotel, but the inside is not going to be familiar.

This frequently-photographed waterfall takes only a short hike to visit.

A roaring, awe-inspiring double cascade of icy water flows through woodland Oregon like something out of a Tolkien novel.

Hundreds of drawings left by the land's previous inhabitants remain mysterious.

Largest collection of mounted dinosaur specimens in the world.