The following is from Wikipedia:
Cherney Maribel Caves was formed primarily by glacial activity during the last ice age. Glaciers wore down the surface of the land and exposed a layer of rock called Niagara Dolomite, forming the naked crags and cliff line in the park.
Since then, the rock has broken down and decomposed, causing caves to form. Around 1892, the first of the caves were discovered on the property of Judge Henry A. Alrich, and was soon purchased by Charles Steinbrecker, who, in 1900, built the nearby Maribel Caves Hotel.
Over the next several decades, many tourists made their way to see the caves. In 1931, Adolph Cherney bought the property, including the nearby hotel. On 5 November 1963, Cherney sold the cave property to Manitowoc County for $16,200, becoming the very first Manitowoc County park.
On August 7, 2014 a pair of tornados ripped through the park and destroyed many of the trees. The park has reopened thanks to the work of many volunteers although many of the broken and uprooted trees remain. I went out there with my trusty Brownie Hawkeye and took these photos of the park and some of the caves, none of which were open at the time because of ongoing maintainence