If you've ever felt like crawling into a cave, there are good opportunities to do so in Wisconsin.
The state is home to around 250 caves, both limestone and sandstone. Some are open to the public. Some are not. Some allow you easy access. Some require you to know how to navigate around under ground.
Probably the best-known cave in Wisconsin is Cave of the Mounds near Blue Mound in South Central Wisconsin. Discovered in 1939, it opened to the public in 1940.
The United States Department of the Interior and the National Park Service designated Cave of the Mounds a National Natural Landmark because the site possesses "exceptional value as an illustration of the nation's natural heritage and contributes to a better understanding of man's environment."
Commonly referred to as the "jewel box" of America's major caves for the variety and delicacy of its formations, Cave of the Mounds is recognized by the Chicago Academy of Sciences as "the significant cave of the upper Midwest."
A guided tour of the cave takes you past a varied collection of colorful stalactites, stalagmites, columns and other formations. The main cavern began forming over a million years ago as acidic water dissolved the limestone bedrock far below the surface.
A lower meandering portion of the cave was formed by the rushing water of an underground stream. The contrast between the chemical and mechanical processes of cave formation is one of the geologic lessons illustrated on the cave tours.
Cave of the Mounds is open year around. Tour times vary by season. You can find times and other information here.
Farther west in the state, near Wauzeka, you can find the Kickapoo Indian Caverns. These caves once were the winter home to Native Americans.
This cave Web site claims to be "the largest show cave in the Midwest. A beautiful centuries old Indian shelter carved by an ancient underground sea and glistening with onyx. We are larger than the Cave of the Mounds." For more information on the Kickapoo Indian Caverns and tours, go to www.kickapooindiancaverns.com.
Not far from the Kickapoo Indian Caverns, near Blue River in Grant County, you'll find Eagle Cave. Discovered by bear hunters in 1849, the cave opened to the public in 1937.
Eagle Cave is the state's largest onyx cave. The cave owners also rent canoes to explore the Wisconsin River near the cave. For more information, go to www.eaglecave.net.
If you want to go to a different part of the state, check out Crystal Cave, along Highway 29 near Spring Valley. This cave offers regular tours from Memorial Day weekend through Oct. 31 and on weekends in April and May.
The cave reportedly was discovered by a 16-year-old farm boy in 1881. It opened to the public in 1942. Beginning in 1992, major exploration began in the cave. Following a major breakthrough made by Blaze Cunningham and Nathan Carlson, the Minnesota Speleological Survey (MSS) led by David Gerboth, has almost tripled the length of the known cave.
A new survey of the cave is in progress, spearheaded by John Lavass and Dawn Ryan, members of the Wisconsin Speleological Society (WSS). Data collected from this survey will be incorporated into the most detailed map of Crystal Cave to date.
For more on this cave and tour times, go here.
Ledge View Nature Center near Chilton also has three caves that can be explored. These are more primitive than some of the other public caves in the state, with no electricity and concrete walkways, but still offer a great caving experience. These caves also are homes to rare moths during certain times of the year.
There are other caves in the state not open to the general public, but places where research and serious cavers do exploration. For example, one of the three largest bat hibernation sites in North America is an old mine near Iron Ridge in Dodge County, now preserved as the Neda Mine Bat Sanctuary.
The old iron mine, abandoned in 1914, was donated to the University of Wisconsin-Milwaukee in 1975. It's home to more than 500,000 bats that migrate here from at least a four-state region. Bat researchers love the place.
Excavators recently unearthed what are believed to be some of the oldest prehistoric bones discovered in a cave in Wisconsin, according to a University of Wisconsin-Green Bay professor.
The bones have been dated to between 5,600 and 5,800 years old, said Prof. John Luczaj, an earth science professor. They were discovered in New Hope Cave at Cherney Maribel Caves County Park in Northeast Wisconsin in January and February.
One of the best articles on Wisconsin caving in recent years was written by Judy Nugent, who hosts "Outdoors Radio" with Dan Small and produces feature segments for WMVS-TV's "Outdoor Wisconsin" show. You can find that article here.