A Texas cave network is home to some of the world's most spectacular-looking and bizarrely named mineral formations.

North Carolina's finest examples of Native American pictographs have survived for 5,000 years.

Only known mainland rookery of the threatened Stellar sea lion.

The longest continuous lava tube in Oregon.

Giant pinnacles in the sun-scorched lands of Southern Utah have been nicknamed "white ghosts."

An obscure waterfall that looks like something out of a fantasy novel.

This historic national park is covered in the stunning ruins of red rock pueblos.

One of the most scenic falls in Massachusetts has a history of death and grim legend.

Bad farming practices caused this unnatural natural wonder.

The site of murders and Satanic cult gatherings.

This concert pavilion on the shore of the Great Salt Lake has been destroyed by fire, water, and disinterest but keeps coming back.

This naturally heated mountainous creek has created a group of neon blue pools of potentially deadly boiling water.

This rare example of a "tidefall" is a spectacular drop from the cliffs down onto the beach.

This massive redwood tree has a hole in the base big enough to drive through.

The lowest point in North America is home to an undrinkable pool surrounded by fields of geometric salt flats.

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.

Once thought to be the oldest living tree in the world, Methuselah was germinated before the Egyptian pyramids were built.

Tour the world's largest deep-hole dimension granite quarry, where you can view the plant where gravestones are made and roll a ball down the outdoor granite bowling alley.

Ancestral Puebloan ruins, natural arches, and box canyons abound in this seldom-visited corner of Monument Valley Navajo Tribal Park.

The lush coastal city of Astoria is riddled with forgotten secret sidewalks.

A tiny red pebble marks what may be the quietest outdoor spot in the United States.

The longest living non-clonal organisms on Earth.

When ecosystems collide in the arid Southwest.

An arsenic-filled pool in the Grand Canyon takes on the appearance of a giant, overflowing pumpkin.