(stream flowing) - Flowing water is the lifeblood of a cave.

You're at Cherney Maribel Caves County Park and Northern Manitowoc County.

Maribel New Hope Cave is one of only five show caves in Wisconsin.

We've been to the highest mountain on earth, Mount Everest.

Over 29,000 feet.

We've been six or seven miles down in the Mariana Trench off from Southeast Asia.

We've had 14 people go up to the moon.

Yet, there's areas of this cave, Maribel New Hope Cave that have had more people on the moon then seen that part of the cave.

(soft percussion music starts) This is the last frontier.

(wind howling) - This is Maribel New Hope Cave.

This is the largest cave that we have here in the park.

What you see is a big voided area which was not a voided area when we first started excavating in the cave here.

We actually hand dug this whole cave out.

And in the restoration work we're doing we're not actually creating a cave, we are restoring it.

So this is what it looked like before the glaciers filled it in.

This is a type of limestone.

The really technical term is Dolomite.

For Wisconsin, has a little bit more magnesium in the rock.

So it's a little bit tougher.

Now you see the big caves that they have down in Kentucky and stuff that's more limestone and it's easy, more easily dissolved in Carbonic acid which forms the cave.

And so that's why they have bigger caves.

So this is really unique for Wisconsin that we actually have this big of a cave and takeaway is called Dolomite.

Now we've had different geologists in the cave here that have over time have told us that there were two glaciers that filled up this cave.

Lower than half the cave was about, the glacier came through about 24,000 years ago.

The upper level was about 12,000 years ago.

As far as filling the material.

- I like to say we're restoring it to its natural beauty.

It's been a lot, a lot, a lot of work.

A lot of yards of sediment have come out of that cave.

Scenes that was filled almost completely to the top with sediment.

- Well, we know there are at least 400 caves that are documented in Wisconsin.

Never hear about them 'cause all our caves are filled in with material from the glaciers.

Certain areas 'cause in Wisconsin, you know, the Southwestern part of Wisconsin is the Driftless Area.

There's more caves down there just because they weren't covered up or destroyed by the glaciers.

Yeah, but we know that there are 400 documented in Wisconsin and they estimate that is only about 10% of the actual caves that are in the state.

(wind howling) Big draw as far as excavating in the caves.

You know, we don't know where these passage goes.

You could actually break into a big cave, opening void area.

(wind howling) We just don't know what we're going to find.

If we just go just another couple inches, you know, we're going to break into something new.

(soft percussion music ends)