Spook Cave is a flooded cave located about seven miles west of McGregor, Iowa

McGregor, Iowa

McGregor is a city in Clayton County, Iowa, United States. The population was 871 at the 2000 census. McGregor is located on the Mississippi River across from Prairie du Chien, Wisconsin. Pike's Peak State Park is located just south of the city...

 in rural Clayton County, Iowa

Clayton County, Iowa

-2010 census:The 2010 census recorded a population of 18,129 in the county, with a population density of . There were 8,999 housing units, of which 7,599 were occupied.-2000 census:...

. It is privately owned and is operated as a tourist attraction. One can take an escorted boat ride into the cave. The cave was first discovered in 1953 and opened for business in 1955.

There is a campground with full service for RVs.

The cave is in the drainage of Bloody Run Creek

Bloody Run (Iowa)

Bloody Run is a creek tributary to the Mississippi River. It mainly flows through Clayton County, Iowa. It enters the Mississippi below Marquette, Iowa and just above Prairie du Chien, Wisconsin on the opposite shore. Bloody Run contains a single railroad track which have variously belonged to the...

, a small tributary of the Upper Mississippi River

Upper Mississippi River

The Upper Mississippi River is the portion of the Mississippi River upstream of Cairo, Illinois, United States. From the headwaters at Lake Itasca, Minnesota, the river flows approximately 2000 kilometers to Cairo, where it is joined by the Ohio River to form the Lower Mississippi...

. A lock and dam maintain water levels. Geologically, the cave is in the Driftless Area of Iowa, a region characterized by karst topography

Karst topography

Karst topography is a geologic formation shaped by the dissolution of a layer or layers of soluble bedrock, usually carbonate rock such as limestone or dolomite, but has also been documented for weathering resistant rocks like quartzite given the right conditions.Due to subterranean drainage, there...

, cave

Cave

A cave or cavern is a natural underground space large enough for a human to enter. The term applies to natural cavities some part of which is in total darkness. The word cave also includes smaller spaces like rock shelters, sea caves, and grottos.Speleology is the science of exploration and study...

s, sinkhole

Sinkhole

A sinkhole, also known as a sink, shake hole, swallow hole, swallet, doline or cenote, is a natural depression or hole in the Earth's surface caused by karst processes — the chemical dissolution of carbonate rocks or suffosion processes for example in sandstone...

s disappearing streams, and cold springs.