The world's longest known cave system.

The only bridge in the United States where BASE jumping is legal without a permit year-round.

One of the "twins" in these falls on the Snake River was sacrificed for hydropower generation in the 1930s.

Where the famed daredevil attempted to launch himself across a canyon in a custom-built rocket.

This museum glorifies the humble potato.

This historic Union Pacific Railroad depot is a stunning symbol of American post-Civil War progress.

This archaeological dig site and museum is home to one of the largest dinosaur fossil collections in the world.

The world's largest mineral hot springs is home to a herd of bison, a free public bath house, beautiful mineral formations, and a terrifying swinging bridge.

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.

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

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

A beautiful geyser under environmental threat.

The first declared National Monument in the United States.

In 1952, this restaurant began selling the Colonel's “secret” recipe.

The largest island on the great salt lake is home to curious creatures and strange stories.

A tunnel with windows, so you don't miss out on the impressive views.

The fifth-longest natural arch in the world, and the longest outside China.

Come for the speed, leave in love with the desert.

The location along the shores of the Great Salt Lake of what was once called, "The Coney Island of the West", now sits barren due to arson and time.

The marker offers a rare chance to be in four U.S. states at once, though there's some controversy over its geographic accuracy.

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

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.

The metal bird, nicknamed "Sandy," stands nearly 40 feet tall and is an homage to the birds that migrate through North Dakota every year.