Bring your own cardboard to the slippery slopes of concrete hidden in a neighborhood park.

A psychedelic labyrinth on the San Francisco bay.

An artsy hidden staircase leads to breathtaking views of San Francisco.

A huge musical instrument played by the ocean.

The second largest waterfall by volume in the U.S., Willamette Falls is outdone only by Niagara in the amount of water that is pushed northward.

Marta Becket's hand-painted theater in the desert.

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

A popular tourist cave with a dark past.

Under the right circumstances, this waterfall in Yosemite briefly turns a luminescent fiery orange.

Celebrating the transformation of trash into objects of beauty.

This 19th-century museum inside of a lighthouse is only accessible during low tide.

A lighthouse built to save lives that took quite a few with its treacherous location.

Sunset-colored dunes of volcanic ash make taking a poor photo impossible.

Trails through lava-carved tube-caves display sparkling bacteria and a rich history.

This nature center has one of the largest collections of native raptors in the Pacific Northwest.

A rugged lava field dotted with molds of the ancient pines that were growing when the volcano erupted.

The longest continuous lava tube in Oregon.

A sprawling cave network created by a lone lava tube.

Unknown to many, this sparkling turquoise lake hides amid Oregon's snowcapped mountains.

The trunks of 3,000 year-old trees lurk beneath the surface of this crystal clear lake in Oregon.

Hollowed out cedar log tubs set in an ancient towering forest.

A volcanic fissure over two miles long and up to 70 feet deep.

The deepest lake in the United States, and once the site of epic destruction that lives on in legends.

At the base of Steens Mountain resides an otherworldly desert.