Much of this 73-square-mile national park is located beneath the Chihuahuan Desert

The Final Jeopardy clue for Thursday, June 19, 2025, fell under the category “U.S. National Parks” and led contestants underground—literally. The clue was: “Much of this 73-square-mile national park is located beneath the Chihuahuan Desert.”

 What is Carlsbad Caverns?

This intriguing clue pointed to one of America’s most unique geological wonders, nestled beneath the arid expanse of the Chihuahuan Desert in southeastern New Mexico. The national park in question spans a modest 73 square miles on the surface, but its true marvel lies below—home to more than 119 known caves formed by sulfuric acid dissolution. Among these is the famed Carlsbad Cavern, an immense limestone chamber renowned for its size and stunning rock formations.

A Hidden World Beneath New Mexico

Carlsbad Caverns National Park was established in 1930 and continues to be one of the most geologically significant sites in the National Park System. While most parks are celebrated for their landscapes above ground, Carlsbad’s distinction comes from its subterranean network, where vast chambers, stalactites, stalagmites, and other speleothems stretch beneath the desert floor.

The park’s largest cave chamber, the Big Room, is nearly 4,000 feet long, 625 feet wide, and 255 feet high at its tallest point. It ranks as one of the largest underground chambers in North America. Visitors can descend over 750 feet into the cavern via elevator or footpath, entering a world that seems completely disconnected from the bright, dry desert above.

Geological Formation and Ecosystem

The caves at Carlsbad Caverns weren’t formed by flowing water, as is common with many limestone caves, but by a rare process involving hydrogen sulfide gas from petroleum deposits. This gas mixed with groundwater to create sulfuric acid, which slowly dissolved the surrounding limestone and carved out massive underground voids.

Despite being in the middle of the Chihuahuan Desert, the cave system sustains its own unique microclimate. Temperatures remain around 56 degrees Fahrenheit year-round, with high humidity. While the surface desert sees dramatic temperature swings, the caverns offer a steady environment that supports various cave-adapted species, some of which are found nowhere else in the world.

Human History and Discovery

Though Carlsbad Caverns gained national recognition in the 20th century, the caves were known to Indigenous peoples long before. Evidence suggests that Native American groups were aware of the cave entrances and used them for centuries. The park’s modern history began in the late 1800s, when a teenage cowboy named Jim White explored the caverns and later helped promote their beauty through photographs and guided tours.

Carlsbad Caverns became a national monument in 1923 and was later designated a national park. In 1995, it was named a UNESCO World Heritage Site due to its outstanding universal value and exceptional cave formations. It remains one of the most visited cave parks in the United States.

A Standout Final Jeopardy Clue

This Final Jeopardy clue offered a classic example of how the show often blends geography, science, and national heritage into a single line of trivia. The phrasing encouraged contestants to consider national parks that are known more for what lies beneath than what’s visible above. With its entire identity centered on an underground landscape in a remote desert setting, Carlsbad Caverns fit the description perfectly.

By highlighting this national park, the clue also served as a reminder of the diversity found within America’s protected lands. From canyons and mountains to coral reefs and underground caverns, the National Park System encompasses a range of ecosystems and geological phenomena. Carlsbad Caverns stands as a testament to the unseen wonders that exist just beneath the surface.