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

The cavern’s main chamber is so vast that the Statue of Liberty could reportedly fit inside it.

California's longest-running tourist attraction is a stump.

The flow from this waterfall sometimes comes out of springs below its rim.

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

Atop an active stratovolcano, two lakes separated by a narrow strip of land.

The longest continuous lava tube in Oregon.

Spectacular volcanic cliffs along the Crooked River invite hiking, rock climbing, and photography.

The original span of a high bridge across the deep Crooked River Gorge has been preserved for pedestrian use.

Multiple waterfalls and several historic CCC buildings anchor this state park in Oregon's Willamette Valley.

This extravagant Art Nouveau rest stop features a million-dollar view of the Columbia River.

Boats and fish both find their way through this massive hydroelectric structure.

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

The highest point in Washington state is a volcano covered in glaciers.

Memorial commemorating the deadliest landslide in U.S. history.

This sci-fi gazebo located in a Washington power town is made from old bits of industrial electrical equipment.

The illuminated falls are a gem in North Cascades National Park.

This historic bridge connects Whidbey Island to Fidalgo Island across whirlpool-filled waters.

Stroll through a wonderland of stupendous moss-covered trees.

A surreal landscape where fanged rocks rise from the ground and the ocean feels like a great mystery.

Shoreline strewn with the remains of ghostly fallen trees.

This tree has witnessed nearly 1,000 years of history.

This large Sitka spruce that appears to be floating in mid-air, has defied logic for years.

Standing 191 feet tall and measuring more than 55 feet in circumference, this is the world's tallest spruce tree.