New fungal and bacterial species call this deadly lake home.

Multiple monuments to a grizzled old mutt that survived the landscape of Butte's treacherous Berkeley Pit.

These giant metal horses graze on a hilltop near the Montana highway.

A stealthy Apache hideaway that became the haunting site of a mass grave.

The recurring nature of this geographic feature might make it unique in the world.

Steep canyon walls hide a forested oasis in the West Texas desert.

The second-largest cave chamber in the world was discovered in 1898 by a 16-year-old and a friend known as "Pothead."

Twice a year, visitors can tour the desolate site that birthed the Atomic Age.

A spring-fed pool so deep it's used for scuba diving as well as swimming.

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