Aqueducts have dramatically changed this old lake, now home to tufa towers and its very own species of tiny brine shrimp.

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

Towering basalt columns, a creation of fire and ice.

An underground mansion with fruit-bearing trees and grapes growing beneath the surface of central California.

An extraordinary mixture of natural beauty and man-made phenomena.

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

Massive crater in central Oregon.

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

Oregon's unexpected high desert, displaying layers of time in a colorful show.

The longest continuous lava tube in Oregon.

Only known mainland rookery of the threatened Stellar sea lion.

Mountain known by the Tillamook Tribe as "the place of the supreme deity."

Two massive rock outcroppings on the Oregon coastline.

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

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

The world's third-largest scale model of the planets.

This striking art museum holds an amazing series of curiosity cabinets.

Robots, lasers, and whoopee cushions, oh my!

Home to the world's largest refracting telescope and the birthplace of modern astrophysics.

Paranormal activity on the great lakes.

A six-story-tall golden pyramid, surrounded by a moat.

Recognized the world over as the home of the McCallisters in the 1990 movie "Home Alone."

World's second largest particle accelerator, where nature reveals its secrets.

Museum dedicated to the art of cutting and polishing stones.