I didn’t come here for a geology lesson. Steeping in Giggling Springs, on the banks of the Jemez River in northern New Mexico, churning hot water kneads my skin and drains my brain. Soon the only thought I can articulate is “this feels nice,” and I find that I’m not terribly curious about the subterranean plumbing that makes this spring so soothingly hot. My husband, however, is much more interested.

“It’s pretty cool that we’re soaking in a volcano,” Ben says. I nod, entranced by the beams of sunlight weaving through the nearby willow trees. We’re not really inside the volcano, of course—more like on the flanks of it, at a privately run bathing facility reminiscent of a backyard hot tub—but I’m too relaxed to insist on the clarification. His next comment, however, pierces my reverie: “We’d be so hosed if it erupted right now.”

Which, of course, the volcano could do. Dormant volcanoes don’t always give fair warning when they’re about to blow. Just last year, Indonesia’s Mount Sinabung displaced 30,000 people when it exploded after 410 years of quietude. New Mexico’s Valles Caldera, which heats the water Ben and I are enjoying, hasn’t erupted in 50,000 years. During that eruption, Valles Caldera spewed out six times as much magma as Oregon’s famous Mt. Mazama (which birthed Crater Lake), and blanketed the earth for miles with several feet of ash. Geologists estimate we’ve got another 45,000 years before Giggling Springs becomes a risky place to soak. Then again, volcanoes set their own schedules.

My fascination with American Indian ruins—not with volcanoes—is what initially drew us here. We planned to explore the Ancestral Puebloan dwellings at Bandelier National Monument, one hour from Santa Fe, and then head west for hiking and trout fishing at Valles Caldera National Preserve, an 89,000-acre tract of mountains and meadowlands that’s poised to become the next addition to the country’s National Park System. We wanted to camp at Jemez Falls Campground and dip into the hot pools near the town of Jemez Springs. Our entire itinerary sat on a 30-mile stretch of NM Route 4, so we could easily hit it all in a long weekend.

Once here, though, we begin referring to our road trip as the Tour de Volcano. Everywhere we go, the explosive theme is unmistakable—even among Bandelier’s ruins, which are our first stop. The monument is famous for its dense concentration of Ancestral Puebloan ruins, including evidence of two-story dwellings, subterranean rooms called kivas that were used for religious ceremonies, and rock art painted and carved on area alcoves. Standing at Long House after a 1.2-mile hike along the Main Loop Trail, I’m struck by how different this looks from ruins I’ve visited in Colorado and Utah. The coral-colored surface is named “tuff,” but it’s not actually tough at all. Reminiscent of Swiss cheese, the cliffs—formed by compacted volcanic ash deposited during eruptions at Valles Caldera thousands of years ago—are so soft that the Ancestral Puebloans bored into the terrain to create homes rather than erect stacked-rock dwellings. Their round entrances look similar to the nests that mud wrens build into canyon walls, and as I climb a wooden ladder and step through the O-shaped entrance to one such dugout, I can’t help but admire the designers’ ingenuity.

Later we head to Jemez Falls, a U.S. Forest Service campground near the midpoint of our excursion, and pitch a tent among the pines. We rise early the next day and drive a couple miles west on Route 4 to the Ridgeback Cafe for plates of huevos rancheros with homemade red and green chile. Then we hit Valles Caldera National Preserve for some morning trout fishing.

Even with my geologically untrained eyes, I can make out the massive caldera. Sweeping grasslands fill its center, which spans some 14 miles across, and is surrounded by a ring of rounded mountains that forms the volcano’s rim. It’s a smaller version of Wyoming’s Yellowstone, which measures 44 miles across. Like Yellowstone, Valles Caldera’s landscape contains hot springs, striking thermal features, and other unique sights. However, some of the preserve is currently off-limits to the public. The land the preserve sits on was a privately owned cattle ranch until the federal government bought it in 2000. Unfortunately, its original budget proved too paltry to develop more than a smattering of visitor services, so activities are restricted to certain areas, and fees are charged to bring in much-needed revenue. Hiking on former logging roads, fishing the two streams at the headwaters of the Jemez River, and horseback riding (all ranging from $10 to $35) are offered by permit only and restricted to certain areas. But all that could change should Valles Caldera be granted National Park Service status, which would increase its annual federal funding, and pending legislation proposes to do so.

After signing in at the visitors center for our assigned stretch of water—quotas regulate fishing pressure and ensure solitude—we drive 30 minutes to San Antonio Creek in the northeast corner of the preserve. We spend a few hours stalking skittish wild trout until the afternoon winds tangle our fly lines. After a picnic lunch (the preserve has no food-service facilities), we head to the southern edge of Valles Caldera to hike the Coyote Call loop. A spur trail leads us to the top of Rabbit Ridge, on the caldera’s south rim, where a talus field creates a clearing in the pines and affords huge views over the landscape. To the south, we survey Bandelier’s rosy tuff, which gives the entire horizon a pinkish hue. To the north lies Valles Caldera’s sweeping meadows, bathed in golden late-afternoon light. Grazing elk look like tiny specks on the distant plains, and beneath our boots, black obsidian glitters in the rocks, reminding us of the incredible heat and strength that hide beneath Valles Caldera’s placid surface.

After a sweaty day of fishing and hiking, we’re eager to experience a tempered version of that heat. We consider making the three-mile hike from our campground to McCauley Warm Springs, an undeveloped spot tucked among the pines, but we opt instead for an easy-access soak at Giggling Springs—a drive-up, fee-assessed facility in Jemez Springs that was the site of the town’s first bathhouse, built in the mid- to late-1800s. About 4,000 soakers each year surrender to the volcano’s more soothing side by easing into the cement-lined outdoor pool, about 30 feet across, nestled into the grassy banks of the Jemez River. Sun, moon, and Buddha sculptures sit within the surrounding gardens, and a black-and-white cat lounges at the water’s edge, enjoying the springs’ warmth without their wetness. Fruit smoothies are the house specialty, and the proprietress delivers mine poolside. As my pruny fingers wrap around the beverage, I sink deeper into the water, which emerges from the ground at a searing 139 degrees but cools to a comfortable 104 degrees in the pool.

“Fire and ice,” I say to Ben as I sip on my smoothie. No showy displays of molten lava erupt from Valles Caldera—at least, not at present. But the steaming water, I realize, is my kind of volcanic power; the kind that appeals not just to the eyes, but to every last inch of my body.

Kelly Bastone is a 5280 contributing writer. Email her at letters@5280.com.