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

The hike through a narrow river flanked by the 2,000-foot-tall walls of Zion Canyon is one of the best in the world.

Giant, natural amphitheaters made of delicate geological formations called "hoodoos."

A sealed test tube said to hold Thomas Edison's dying breath was given to the inventor's friend and mentee, Henry Ford.

Giant six-pack could provide one person a six-pack a day for 3,351 years.

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

The rocks in this arid basin leave trails of movement behind them.

This old mining town, deep in the California desert, has a year-round population of one.

Ten 25-foot-tall, beehive-shaped kilns, abandoned in Death Valley.

An abandoned Jazz Age dream home and con man's hideout in Death Valley.

A massive hydrovolcanic explosion left a half-mile wide crater in Death Valley.

The highest dunes in California are the most likely place in the area to hear the Singing Sands.

Travelers leave tea kettles in a remote part of Death Valley as part of a mysterious, decades-old tradition.

Quite simply the largest tree in the world (by volume).

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

Towering basalt columns, a creation of fire and ice.

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

The largest hot spring in the United States is, as the name suggests, a stunning show of natural color.

An architect's childhood fantasy treehouse made real.

A beautiful geyser under environmental threat.

One of nature's most well-scheduled phenomenons resides in Wyoming's Yellowstone National Park.

The only natural lake in the world that drains into both the Atlantic and Pacific Oceans.

This Yellowstone geyser may not shoot as high as the nearby Old Faithful, but it erupts for considerably longer.

The granddaddy of all tourist traps, built on ice water, jackalopes, and a giant dinosaur.