Getting lost in the caves of Tennessee

As a freight train of water pummels me from 85 feet above, I am no longer hot, sticky or stressed. I just am. The relentless pour drowns out all thoughts except “aaaahhh.”

Nature offers two sure cures for cooling the body and clearing the mind: waterfalls and caves. Both chill-thrills are native to central Tennessee's swath of the Cumberland Plateau east of Nashville. Here to research endangered species, I've found an ideal summer refuge for overheated Homo sapiens.

Given the breathtaking plunges of Fall Creek Falls State Park, it's no wonder that the 1994 version of “The Jungle Book” was filmed here. Come evening, inky skies and Zen-zone temperatures lure stargazers. A short roller-coaster drive beyond the park, past wildflowers and graves covered with tented slabs of stone, takes you to a cave with its own waterfalls.

Locals keep mum about these geological gems, but some friends spilled the secrets. Stuart Carroll, a naturalist, and Chuck Sutherland, chairman of the National Speleological Society's Upper Cumberland Grotto, are crusaders for endangered native species, chiefly hemlocks being felled by a tiny bug and bats ravaged by a fungal disease called white-nose syndrome. They also know literally cool places to play.

For centuries, people showered in the falls and conducted purification rituals in the caves. Dressing to navigate Lost Creek Cave near Sparta, I yank Chuck's elbow pads over my pant legs to protect my knees. We snap on helmets with headlamps and grab flashlights, because Lost Creek is cloaked in total darkness.

We're hiking land once owned by Chuck's ancestors. Caves have traditionally hosted religious ceremonies, moonshine distilling, mayhem and the occasional murder. These days, bad cave behavior involves graffiti, littering and ignoring proper spelunking protocol — showing respect for the fragile ecology and decontaminating post-caving to avoid spreading any fungus. That means strip and change, bag your clothing for laundering and use disinfectant wipes on your hands, face, helmet and boots.

Tramping into the sinkhole, we enter a misty microclimate. The sound of rain leads to a lush cove facing a 60-foot waterfall; think “Avatar” without supersaturated hues. Refreshed by the spray, we enter the cave's gaping maw and snap on our lights.

I scramble while Chuck billy-goats down long expanses of rocks, many wobbling. Overheating's no threat in this constant 56-degree climate, but the rough limestone can meat-grind the skin. So tough stretches require maintaining at least three points of contact (any combination of hands and feet). Going down some boulders, I choose five, “smearing” down on my rump. We look for petroglyphs, but any ancient drawings are obscured by crude contemporary markings — school names, lovers' initials. The urge to deface confounds Chuck: “Do people think this improves upon nature?” Equally baffling: Why fools don't take out their bottles, cans and tobacco tins. We pick up litter on the way out.

But hiking in, I'm watching my step and the underground landscapes: rooms both Lilliputian and large enough for tractor-trailers, clouds hovering over ledges, a stream leading to a spectacular 40-foot indoor waterfall. A figure materializes overhead: Spider-man Chuck balancing on a ledge. I venture into the misty veil, ready for spiritual renewal, eternal youth, at least a free facial.

Few bats appear, perhaps because of white-nose syndrome. But pools harbor tiny fish that have lost their eyesight in adapting to the pitch-blackness. I get a taste of that world as my oversized helmet lists saucily to the side, blocking my right eye. Even though I do yoga, I'm not adapted to slithering belly-down through narrow slots, but this transport mode rouses vestigial muscles and enables micro-sightseeing.

In an ancient room of rock, Chuck calls lights out. We're bathed in absolute darkness, hearing only water in the distance. So peaceful, a perfect antidote to traffic, babble, ringtones. But, says Chuck, the sensory deprivation “has driven people mad.” A momentary flare of real life: I must update my will.

The 2011 Tennessee Cave Survey documented about 9,600 caves in the state, more than in any other. This part of the Cumberland Plateau has about 5,700; Chuck explains that sandstone cap-rock allows water to seep into the limestone below. “Where water hits limestone, dissolution occurs, and over geologic time, caves form.”

Lost Creek Cave lacks the ornate stalactites and stalagmites of nearby show-cave Cumberland Caverns, with its spotlights, railed stairways, underground concert hall, reclaimed New York theater chandelier and Creation-themed light show. Instead, it offers adventure, raw nature and discoveries such as animal bones. A careless explorer “destroyed tracks made by a Pleistocene-era jaguar in one cave,” says Chuck, noting that grottos — caving clubs — teach proper techniques and conservation.

The next day, Stuart and I hike around Fall Creek Falls State Park, about 25,500 acres of cool spots including trails, waterfalls, creeks, swimming havens and a steep cable trail that's a quarter-mile up and feels like two miles going down. From one overlook, we view the thundering namesake falls (at 256 feet, the highest free-fall waterfall in the eastern United States), then miles of treetops from a stone outcrop on which sprouts a lone Virginia pine. A swinging footbridge over the gorge provides views of ospreys, red-tailed hawks and turkey vultures, photo-snapping grown-ups and children playing hide-and-seek among the boulders. They don't realize that much of the forest teeters on the brink of extinction.

Stuart points out small cottony tufts at the base of hemlock needles, signs of the aphid-like hemlock woolly adelgid. Eastern hemlock, nicknamed “redwood of the east,” can reach 150 feet on trunks six feet wide. Yet these tiny insects from Asia have killed more than 80 percent of the Shenandoah Valley's hemlocks over two decades. Now, they are spreading into the Southern Appalachians via wind, migratory birds and humans.

We're hiking in one of the world's largest stands of hemlocks, some 400 years old. Their loss would change the region's ecology, between countless fallen trees, loss of stream-cooling shade, higher temperatures and oxygen depletion. With the trees goes animal habitat — research has found that 96 percent of wood thrush nests are in hemlocks. Combating the trees' destruction involves injecting a nicotine-derived insecticide, imidacloprid, the active ingredient in dog tick and flea medication. Biological control — unleashing adelgid-eating beetles — is also under consideration.

I imagine legions of syringe-wielding park rangers as we loop down to the creek bed, passing fragrant spirea, spice bush blooms, iridescent blue damselflies and a humongous split boulder from which chilly air pours. “That's the A/C vent,” jokes Stuart. No stopping; there's a mile of creek-rock scrambling and swimming ahead.

Moss and algae slip hazards deter us from hopping across what Stuart calls “God's rock garden.” Three-point contact prevents cheese-grated skin and unwelcome deep-tissue massages.

And then, about the time when big-city streets practically burst into flames, we arrive at Cane Creek Falls. Stripping down to our swimsuits, we slip into the 60-foot-deep pool for baptism by the 85-foot plunge. It drums a message: Savor and save these wild places.