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A Cave Kingpin Is Buying Up America’s Underground. What’s His Plan?

Matthew Sherrill
6-8 minutes

Ackerman at the natural entrance to Tyson Spring Cave

Ackerman at the natural entrance to Tyson Spring Cave (Photo: Matthew Sherrill)

Caver Kirk Moorhead (left) and Ackerman in Holy Grail Cave in 2017

Caver Kirk Moorhead (left) and Ackerman in Holy Grail Cave in 2017 (Photo: Courtesy Martin Larsen)

On an unpleasant, damp Saturday in late October, Ackerman and I drove through Fillmore County in his van, stocked with helmets, gloves, headlamps, cave suits, boots, arm pads, kneepads, and wetsuits, along with an assortment of ropes and harnesses that I hoped we wouldn’t be using. Our destination was Holy Grail Cave, whose exact location I didn’t yet know. The sites of Ackerman’s cave entrances are kept largely under wraps, though some of these secrets are more closely guarded than others. The basic principle is that unwanted attention can lead to unwanted visitors, and unwanted visitors can lead to irreparable, if inadvertent, damage. Accordingly, entrance to the caves, while free of cost, requires Ackerman’s permission, as well as the hiring of a sanctioned guide and the signing of an ominous waiver that itemizes 23 distinct risks one might face underground. (The more casual spelunker can opt for the state-run Mystery Cave or tours of the nearby, privately operated Niagara Cave.)

Eventually, we pulled over at an Amish farm across the street from a field that contained the Holy Grail entrance. Ackerman had been leasing his plot to the farmer and needed to finalize some paperwork, as well as have a firm conversation about overgrazing that had reduced one corner of the land to a sad patch of dirt.

After steady rains, the driveway and surrounding grounds had been churned into a deep, viscous muck. A few chickens strutted around the decaying silos and rusted-out farm implements, and a rangy dog, one hind leg hopelessly mangled, hobbled forth to greet Ackerman as he stepped out of the van. As it happened, a disheveled, heavyset neighbor in paint-spattered jeans was also waiting to visit with the farmer. They spent a few minutes in friendly conversation before I heard Ackerman say, “You know, I own the cave across the street.” He proceeded through a few caving anecdotes before asking about the man’s own tract of land. “Are there sinkholes on the property?” It turned out there were two. Ackerman darted back to the van, where I already had his business card ready, and returned to the neighbor, now a promising, potential new conduit to imperial expansion. “Here,” Ackerman said, handing him the card. “Just call me.”

Once we had crossed back over the county road, I discovered that the entrance to Holy Grail was, like the way into Tyson Spring, a lidded, three-foot-wide metal culvert pipe poking inconspicuously out of the earth in the far corner of a field. Once again there was a padlock, the only visible security measure, dangling from the exterior of the shaft, so I asked the obvious: What’s to stop a prankster, or one of the myriad enemies Ackerman had made over the years, from securing the lock and forever consigning him to his own sunken empire?

“Aha,” he replied. “Watch.” He leaned over and showed me a mechanism on the shaft’s interior. Swiveling two levers, he demonstrated how the entire locking component would then fall away, freeing whomever might be trapped inside. “It was one of the first things I thought of.” 

Down below, southern Minnesota’s wettest year on record had left every surface of Holy Grail plastered in several inches of mud. As a relative spelunking novice, I found myself spending much of the time yanking my boots out of particularly deep patches or clawing desperately at anything dry to anchor myself on the cave’s slippery slopes. Ackerman—some 30 years my senior—was scampering up inclines and over rubble with ease, never seeming to falter. He knew the rock’s nuances, a kind of second-nature response to each challenge it presented. He stayed relatively clean; I began to grow less and less distinguishable from the mud-coated features around me.

Not that Ackerman would ever call himself a purist—developing each of his caves has involved excavation, dirt clearing, debris removal, and, of course, blasting.

During one merciful breather, Ackerman indicated a narrow chasm, tossing a rock down to give a sense of its depth. We heard it land four seconds later, clattering between the side walls before plunking into a pool of distant water. Years ago, on an early expedition into Holy Grail with two fellow cavers, Ackerman had ventured alone into the pit, suspecting that it might lead to another navigable passage. He braced himself between the walls, without a rope or harness, and wiggled his way down to a chockstone—a fallen hunk of rock nestled snugly across the shaft. It collapsed. Still wedged above the abyss, he maneuvered down to another chockstone, which also gave way beneath his weight. In the ensuing scramble to stay aloft, he lost his headlamp, leaving him in darkness.

“I heard them say, ‘Is he dead?’” Ackerman recalled. Realizing their mistake, his partners tossed him some nylon webbing, and he was able to climb his way back to safety unscathed.

Ackerman is prone to businesslike narration of such near death experiences. There was the time he almost brought several tons of rock down on his head while experimenting with Kinepak explosives in Spring Valley Caverns. There was the time he almost drowned in a cave after whitewater surged through its tunnels during a sudden deluge. There were the several times that he found himself hopelessly lost in his own caves for hours and had to leave blasting wire on the walls, shaped like arrows, to avoid retracing his own steps as he searched for a way out. And then there was the time in Granger Cave that he dove into a sump—a water-filled passage—carrying an oxygen tank in one arm, got tangled up in his dive line, lost his weight belt, cracked his head against the cave ceiling, and finally broke himself free with a line cutter and managed to blindly navigate the inky waters back to dry rock after some 35 minutes of composed panic.

He tells these stories less to impress, I think, than to remind himself of the sheer strangeness of his vocation. And perhaps more importantly, to reassure himself of his identity as the elect, proper steward of the Driftless underground.

Ackerman in Bat River Cave in 2007

Ackerman in Bat River Cave in 2007 (Photo: Courtesy Jim Edberg)

Spring Valley Caverns in 2011

Spring Valley Caverns in 2011 (Photo: Courtesy Jim Edberg)