John Ackerman established the Minnesota Karst Preserve in 1989 to preserve, study, protect and to promote conscientious exploration and conservation of our unique underground wilderness.
From the beginning, John recognized the need to protect the fragile and timeless environment, both above and underground. Conservation has always been a prime tenet of the Minnesota Karst Preserve.

The Minnesota Karst Preserve owns five preserves in S.E. Minnesota and Northern Iowa, which provides access to 33.5 miles of cave passages. The properties encompass 36 caves, slightly over 500 surface acres and 1,126 acres of additional subterranean cave rights.

CAVE FARM

Located in Southeastern Minnesota, the Cave Farm consists of approximately 500 scenic surface acres combined with 192 additional acres of subsurface cave rights. To date, 32 caves have been discovered on the property including the largest, Spring Valley Caverns

Spring Valley Caverns is the largest privately owned cave in the state and is the most extensive cave system on the Cave Farm. At over 5.5 miles in length, Spring Valley Caverns is rapidly approaching the 100th longest cave in the United States.

After completely excavating all rocks and soil over the three sinkhole entrances to the cave, a sizeable building, mimicking natural limestone, was constructed. It serves as a gathering place for cavers, researchers and nature groups before embarking on their underground journeys.

COLD WATER CAVE

Located in Iowa, just across the Minnesota border, The Minnesota Karst Preserve owns 5 surface acres and 200 acres of subsurface rights to 17.5 mile long Cold Water Cave. One hundred eighty-eight feet below the secure man made entrance lies one of the most prominent and most highly decorated cave system in the Upper Midwest. This cave system, the 32nd longest in the United States, has been dedicated as a National Natural Landmark.

GOLIATH'S CAVE

Located in Southeastern Minnesota, the Minnesota Karst Preserve owns several surface acres and 358 acres of subsurface rights to Goliath’s Cave. Numerous streams have converged to create a vibrant active cave network scattered with rare formations. The exploration and survey of this cave system is currently underway. It is estimated that this cave system will be 3.5-4 miles long after the cave is fully explored and surveyed.

TYSON SPRING CAVE

Located in Southeastern Minnesota, the Minnesota Karst Preserve owns one surface acre above Tyson Spring Cave where a man made entrance was created. In addition, the Minnesota Karst Preserve owns 144.5 subsurface rights to the cave system, it's picturesque natural spring resurgence and 4 outlying caves. The network of spacious pristine passages are currently being explored and mapped. It is estimated that this cave system is 3.5-5 miles in length.

BAT RIVER CAVE

Located in S.E. Minnesota, the Minnesota Karst Preserve owns one surface acre and 231 subsurface rights to this amazingly diverse cave system. A wide stream meanders along the main cave passage, which is lined with unique formations, before it finally drops over a deep chasm and forms a fantastic roaring waterfall. This cave system contains the largest bat sanctuary in the Tri-State area. The three species of bats that rely on Bat River Cave for their roost sites are being studied and monitored by cavers and scientists. Most of this cave was recently discovered, and it is thought that after exploration and survey trips are conducted the cave will exceed 3 miles in length.