Below the surface
By Chris Rogers

Cavers explore miles underground

Hundreds of feet underground a bizarre world exists, a world where streams disappear into cracks in the ground, translucent fins of rock drape twisting passageways, and luminescent spires of rock have slowly grown for thousands of years. There are scores of miles of underground passages in the fractured bedrock of the Driftless Region of Minnesota, Iowa, and Wisconsin. Mystery Cave, Minnesota's longest, stretches for 13 miles. Explorers have navigated 17 miles of passages in Cold Water Cave, which begins northeast of Decorah, Iowa, and reaches across the Minnesota border. Numerous caves lie beneath the hills and fields of Fillmore County alone.

Few people see these places. Fewer still risk their lives to discover new passageways, jamming their bodies through tiny openings, dangling over rocky abysses, and diving in freezing cold water beneath the earth's surface. But for some, caving is a life-long pursuit, perhaps an obsession.

For years, St. Paul caver Steve Porter has plunged over and over into murky depths in one of the most dangerous forms of caving: cave diving. Some cave passages are dry, while some have varying amounts of water dripping, flowing, or surging through them. Others are completely submerged. Sometimes these submerged sections lead to miles of caverns that are only accessible by journeying through the watery fissures. Cave divers use scuba gear to do just that.

"Cave diving is a ticket to a quick death if you're not trained," Porter warned. It requires a lot of gear, too. "Basically you have to have double everything. If you have an equipment failure you can't just go up to the surface."

In southeastern Minnesota, the silt deposited in most flooded passageways creates another issue. Lights can illuminate dark caves, even underwater, but as cave divers disturb the silt around them, they muddy the water and it can become utterly opaque. To find their way back through twisting underground labyrinths, cave divers must drag a safety line behind them. The line is essentially a Hansel and Gretel-style bread crumb trail—it enables them to find their way back out even when they cannot see their hands in front of their faces.

However, the safety line can easily snag or tangle, creating a life-threating situation, Porter discovered on a fateful dive.

Porter was exploring a flooded passageway with his partner when Porter accidentally let the line go slack and becamed entangled in it. Unable to free himself, Porter waited for his partner to help (per cave diving protocol). Though, they had no means of communication, Porter's partner realized what was going on. He struggled to free the line—it was wrapped around Porter and his scuba gear. To make matters worse, Porter had air trapped in his dry suit, causing him to float inside the narrow passageway. The air bubble wound up in Porter's seat and soon he was floating upside down, with less and less air left in his scuba tank, wrapped up in the line that was his and his partner's only ticket out.

"I'm starting to get concerned because I can see all the silt come up," Porter described. "I think, 'My gosh, if he can't get me loose when he can see the line, how is he ever going to do it when he can't?'"

Unable to talk, Porter could only guess what his partner was thinking as he continued fumbling in vain. "I figured he'd start thinking, 'Better to have one fatality than two,' and leave me there," Porter went on.

Porter thought about ditching all of his scuba gear to escape the snare and sharing his partner's oxygen on the way out. Porter felt his partner's hand on his stomach and thought that he, too, had settled on this last ditch effort. Then Porter felt him unzipping the dry suit.

"He was trying to open up my suit and get the air out," Porter explained. "Because I was upside down, he was having a hard time dealing with where the entanglement was." With the air bubble out and Porter right side up, perhaps he could be freed. Cold water rushed into Porter's suit and he was righted, but his partner could still not sort out the line.

"All of a sudden he was gone," Porter said. His partner disappeared into the blackness in the direction of the exit and Porter had no idea what had happened. After waiting what seemed like an eternity, Porter realized his partner must have gone to the surface. Porter had to do something to save himself. He pulled on the safety line, praying the thin cord would not break, and tugged, crawled, and heaved his way through the flooded cave.

Utterly soaked and wrapped up in loops of safety line, Porter fumbled his way to precious air. He and his partner made it out safely that day, but it was just one of many times Porter thought he might die. When asked if the risk ever makes him think twice about going back, Porter said he has thought about staying high and dry, but new caves and new passageways are always beckoning him back down.

Danger and dedication

John Ackerman has gone to tremendous lengths to discover new caverns, as well. The man has rummaged through and shimmied under the wreckage of collapsed sinkholes in hopes of finding openings beneath the precarious rubble. He has used high explosives to blast through sections too narrow to pass through. He has bored entrances through bedrock, and he uses a modified track-hoe (a long-armed backhoe on tank-like tracks) that he calls the "Cave Finder" to excavate sinkholes and create entrances to caverns.

He has also spent a fortune buying land above numerous southeastern Minnesota caves. Ackerman owns the access to most of the area's caves and claims to have discovered over 40 caves.

"I think what attracts me to it is to be the first person to walk through the inky blackness of the unknown. You're the first human being to shine your light through those passages since the beginning of time," Ackerman said. His enthusiasm for caves, he says, "is like a hobby that just got out of control."

Like Porter, Ackerman pointed out the serious danger involved in his choice of activity. "I don't want to say that I'm an adrenaline junkie, but when you do something as dangerous as trying to discover a cave there's a great deal of risk involved. Perhaps the weather can change and you can drown, or if you're in an unstable part of the cave you can hear what sounds like sizzling bacon—that's a rock slide," he described. "In Minnesota we have one added danger: the temperature of the cave is 47-48 degrees. If you're lucky enough only to get stuck in a cave, hypothermia can take you very quickly," he continued.

Ackerman acknowledged that what he does is more risky than run-of-the-mill caving.

"When you're dealing with explosives in caves, if you screw up once, you automatically die. It forces one to be very careful," he explained.

Not all cavers put their lives on the line. "I love thrilling experiences, but I do not have a death wish," said Mystery Cave State Park Manager Warren Netherton. "I do not go into something that I do not fully expect to come out of." Rather than risk death, Netherton and Iowa caver Ed Klosner have devoted years of their lives to mapping caves. Global Positions Systems (GPS) do not work underground, so the mapping of caves is done the same way it has been for decades: by measuring the dimensions and compass bearing of every single room and passageway. Klosner and Netherton have been working on this painstaking process at Mystery Cave since 2006. Netherton estimated they will be done in 20 years. He laughed, but he was not joking.

Mapping caves provides an invaluable record for future cavers and scientists. Despite the effort, it has its own pleasure, too. "Surveying caves is exciting because you get to see the spatial relationships of all those interconnecting tubes," Netherton said. "It's a 3-D puzzle to try to figure out how it fits together," Klosner explained.

Caving and conservation

Some have criticized Ackerman's bravado in creating new entrances to caves as detrimental to fragile cave formations, ecosystems, and groundwater. Ackerman contends conservation is his goal.

Ackerman has put hundreds of acres above and below ground into a private, undeveloped space he calls the Cave Preserve. He has been undisputedly generous in allowing scientists and experienced cavers to study and explore his network of caves. Climate research, cave mapping, and paleontology take place in his caverns. The skull of a saber tooth tiger was found in one of Ackerman's Fillmore County caves, the northernmost site of such a discovery ever documented.

When asked whether expanding access to so-called underground wildernesses is counterproductive to protecting them, Ackerman replied, "That just screams ignorance in huge letters because you can't protect what you don't know exists."

Winona State Univeristy geology professor Toby Dogwiler agreed that allowing people to experience nature is a key part of conservation. "The best way to protect Yellowstone National Park would be to put a fence around and keep everyone out, but if people can't see how beautiful and special it is, then they won't care about it," he said. "You can better conserve caves by making sure that people have access to them," he added.

That said, minimizing one's impact while traveling through a cave is important, Dogwiler said. The oil from human hands can inhibit the growth of stalactites that are hundreds of thousands of years old, so climb and crawl with caution, Netherton advised cave-goers.

The greatest threat to Minnesota caves, Akcerman contends, is not humans below ground but human land use above ground. Agricultural chemicals, manure, and other pollutants make their way quickly to cave waters, he said. Ackerman hopes his Cave Preserve will prevent that at Minnesota's finest caverns.

"Caving has turned me into an avid conservationist because I realized how fragile southeastern Minnesota is," Ackerman explained. "If a tanker tips over, it's going to run into the nearest cave and everybody downstream is going to be drinking that water for eternity."

Klosner described seeing evidence of high-levels of pollution while in Cold Water Cave. "It's eye-opening to be in a cave and see foam in the water from agricultural products," he said.

Hydrology ceases to be an abstract concept after being inside the water cycle and seeing groundwater firsthand, Netherton said. "Caves allow you to see where our water goes," he explained. "What a unique place for people to be able to go: between where rain falls on the surface and the aquifers where it goes."

"Because of years of marketing, people have an idea that spring water is pure," Dogwiler said. "There's very little opportunity for natural processing and attenuation of contaminants [in Karst groundwater]. Whereas in a non-Karst aquifer there's time for chemicals to break down or absorb into clays."

How caves are born

In Minnesota, significant caves only exist in the limestone and dolomite of the Driftless Region. They form when rain water, which is naturally slightly acidic, flows through cracks in the limestone and dolomite bedrock, dissolving the basic (as in high-pH) rocks and creating conduits through the bedrock. "If they are large enough we call them caves," explained Dr. Toby Dogwiler of Winona State University.

In those caves, some of the dissolved rock is left behind by dripping water. Over thousands of years, this forms all manner of oddities, famously the spike-like stalactites and stalagmites. All of the deposits are essentially variations on this theme, but an incredible assortment exist. Passages are alternatively decorated with needle-thin "soda straws," ribbons of "bacon," and oozing blobs of once-dissolved minerals.

This interaction between bedrock and rainwater makes the region's foundations as porous as Swiss cheese. This Karst topography, as geologists call it, leads to caves, sinkholes, and streams that vanish into the underground.

Caving 101

Do not call it spelunking. The term is passé among cavers. They go caving. Sport cavers, cave photographers, cave ecologists—people go beneath the surface for all kinds of reasons, but they all urge would-be cavers to get connected with a caving club or "grotto." Rogue cavers tromping through these fragile and rare phenomena is frowned upon, Dogwiler explains. What is more, caving is incredibly dangerous for beginners, and underground accidents require many people to undertake a risky rescue effort. By connecting with a caving group, novices can learn from experienced cavers. More information is available at (Minnesota Spelogical Survey) and

Mystery Cave State Park offers wild caving tours during the summer. Mystery and Niagara caves also offer more accessible trail tours.

For more information on the Cave Preserve see