From a massive Cold War missile defense pyramid in North Dakota to a cave in Montana deeper than many of the world’s most famous underground systems, some of the most mysterious places in the United States remain hidden in plain sight. A video from Across The Globe explores the least explored place in every US state, with locations ranging from restricted caves and remote wilderness to submerged geological formations and abandoned military sites. Many are difficult or impossible for the public to access, while others remain poorly understood even by scientists.
Hidden Worlds Across America
The video highlights the enormous variety of unexplored terrain across the country. In Alabama, Fern Cave contains more than 15 miles of mapped passages and a massive population of endangered gray bats, while much of the cave remains unmapped. Colorado’s Groaning Cave sits at roughly 10,000 feet in elevation and has more than 15 miles of mapped tunnels. Air moving through cracks suggests the known passages could be just a fraction of the underground system.
In California, Monterey Canyon stretches hundreds of miles beneath the Pacific Ocean. Scientists have mapped only a small portion of the massive underwater landscape in high detail. Other locations are difficult to reach because of extreme hazards. Georgia’s Ellison’s Cave contains Fantastic Pit, a 586-foot vertical drop that ranks among the deepest underground pits in the United States.
Montana Cave Is Deeper Than 2,400 Feet
One of the most remarkable locations featured in the video is Tears of the Turtle Cave in Montana’s Bob Marshall Wilderness. Discovered in 2006, the cave reaches approximately 2,477 feet below the surface, making it the deepest known limestone cave in the United States. Reaching the bottom requires dozens of rope drops through an extremely narrow and cold vertical passage. The expedition is so demanding that explorers have established an underground camp during descents, and extreme conditions have left portions of the cave unexplored.
A Cold War Relic in North Dakota
North Dakota’s Nekoma Pyramid offers a very different kind of mystery. The enormous concrete structure was built during the Cold War as part of the Safeguard anti-ballistic missile system. The project cost billions of dollars and operated for only 133 days before being shut down in 1976. The facility remains heavily restricted and monitored, leaving much of its underground infrastructure inaccessible.
