SPRING VALLEY (AP) — John Ackerman is a big-time landlord of subterranean real estate.
Ackerman, 59, owns Spring Valley Caverns, the largest private cave in Minnesota but just the beginning of his underground empire, which he calls the Minnesota Cave Preserve. He holds the keys to more than 40 miles of caves hidden beneath the rolling farm fields of Minnesota and Iowa and is always seeking more.
"I think it's just to be able to be the first human being to introduce light into the inky blackness of just unknown chambers that may go for miles," he said of his motivation. "And then later it's to protect them so that they're available for scientific research. That's what keeps me going. That's the adrenaline rush, is 'What's around the next corner?'"
Ackerman estimates he's spent $4 million on cave exploration and acquiring underground rights, but he doesn't charge admission to the nature groups, scientists and cavers who visit. It's a hobby made possible by his successful furniture restoration business, he said.
Ackerman, who lives in Farmington, just south of Minneapolis, said he discovered his love for spelunking as a boy when he poked around the caves along the Mississippi River in St. Paul. Spring Valley Caverns was his first acquisition, in 1989, when he bought 600 acres of farmland. A previous owner had tried and failed to commercialize the half-mile-long cave below.
Southeastern Minnesota and northeastern Iowa are prime cave terrain, with soluble rock such as limestone eroded over time by running water. For a person on the surface, sinkholes are a clue to finding caves, said Ackerman, who claims to have discovered 43 caves that he now owns. All but one are in southeastern Minnesota.
Once he finds a cave, Ackerman says he approaches the landowner to buy some surface land with underground rights to the rest of the land. He then has an entrance drilled.