Much of this 73-square-mile national park is located beneath the Chihuahuan Desert
The Final Jeopardy clue for Thursday, June 19, 2025, came from the category “U.S. National Parks” and highlighted one of the country’s most fascinating subterranean landscapes. The clue read: “Much of this 73-square-mile national park is located beneath the Chihuahuan Desert.”
What is Carlsbad Caverns National Park?
This clue steered contestants toward a lesser-known but extraordinary site in the American Southwest. Carlsbad Caverns National Park, located in southeastern New Mexico, stands out not for its surface terrain, but for the expansive cave system that lies beneath the desert. With over 119 known caves formed by sulfuric acid dissolving limestone, the park’s vast underground chambers make it a geological marvel unlike any other in the National Park System.
Carlsbad Caverns: A Park Below the Surface
Carlsbad Caverns National Park covers approximately 73 square miles, but the most renowned features are not found on the desert floor. Instead, they exist in the darkness below. The main attraction, Carlsbad Cavern, contains the famed “Big Room,” the largest single cave chamber by volume in North America. Measuring about 4,000 feet long, 625 feet wide, and 255 feet high, it draws thousands of visitors annually who descend either by elevator or a steep walking trail.
The park is located in the Guadalupe Mountains and sits within the Chihuahuan Desert, one of the most biologically diverse deserts in the world. However, it’s the park’s underground ecosystem that captures scientific and public attention. The caverns are home to unique speleothems—formations such as stalactites, stalagmites, and flowstones—and several species of bats, most notably the Brazilian free-tailed bat, which emerge in dramatic nightly flights during warmer months.
Geological and Historical Significance
The formation of the caverns traces back millions of years to an ancient reef system during the Permian Period. Unlike many limestone caves formed primarily by surface water erosion, Carlsbad’s network developed through the action of hydrogen sulfide gas rising from oil and gas deposits below. This gas combined with groundwater to form sulfuric acid, which then dissolved the limestone and carved out the massive voids that make up the caverns.
Carlsbad Caverns has long captured human fascination. Indigenous peoples, including the Mescalero Apache, knew of the caves, and early European-American settlers rediscovered them in the late 19th century. In 1923, President Calvin Coolidge designated the area a national monument, and it became a national park in 1930. The park was later named a UNESCO World Heritage Site in 1995 for its outstanding geological features.
Scientific Exploration and Preservation
Ongoing exploration continues to reveal new passages and chambers, with researchers still mapping extensions of the cave system. Lechuguilla Cave, discovered within the park boundaries, is among the deepest and most complex caves in the world, featuring rare formations and isolated microbial ecosystems. These discoveries have offered valuable insights for biologists and geologists alike.
Preservation efforts are a top priority, as the delicate cave environment is highly sensitive to changes in temperature, humidity, and light. The National Park Service has implemented strict access controls and educates visitors about minimizing their impact. The combination of scientific interest and visitor education helps ensure that this unique underground treasure remains protected for future generations.
A Fitting Challenge for Jeopardy Contestants
The clue offered on June 19 served as a compelling test of both geography and geology knowledge. Carlsbad Caverns is not always top-of-mind when thinking about national parks, but its striking features and hidden world beneath the desert make it unforgettable to those familiar with it. For Jeopardy, a show known for celebrating curiosity and knowledge, the inclusion of this park was a fitting nod to America’s natural wonders that lie both above and below ground.