The Boquillas Hot Springs, a collection of 105-degree springs located along both sides of the Rio Grande in Big Bend National Park and Boquillas, Mexico, was a popular bathing spot long before settler J. O. Langford arrived in the 1900s and turned the U.S. side into a health resort. Reports from the mid-1800s indicate that the hot springs served as a stopover on the historic Comanche Trail. Records also document Apaches growing crops and living in settlements around the springs as early as the 1700s. In fact, pictographs above the springs provide evidence that ancient peoples constructed bedrock mortars and bathing pools for capturing the warm water. Today, the foundation of the more recent Langford bathhouse still holds enough hot water to create a shallow pool for visitors to enjoy. Located along the Hot Springs Trail just a short hike from the Hot Springs Trailhead, the small pool offers a relaxing respite after a day of winter trekking across the national park.
But how does the Boquillas Hot Springs water get so hot? Water, primarily rainfall, seeps into the ground then circulates deep beneath the surface courtesy of faults, a characteristic of the Big Bend’s basin and range geology that formed between 18 and 23 million years ago. As this water circulates below, it’s warmed in a process called geothermal heating. The deeper the water circulates, the closer it gets to the Earth’s super-heated mantle, coming into contact with hot rocks that heat it up. The circulating water is also under tremendous pressure from rock and soil layers pressing down on it. Faulting again assists in allowing the heated water to find a way back to the surface, where it becomes a hot spring. Unlike many hot springs around the world, in which temperatures are boiling and the pressure drives the water back to the surface in shooting geysers, the national park’s hot spring bubbles up gently and is just warm enough to sooth tired feet. But don’t stay submerged for long. Whether soaking in a natural hot spring or human-made hot tub, raising the body’s core temperature above 98.6 degrees for too long can be dangerous.