By OnMilwaukee Staff Writers   Published Jun 09, 2011 at 9:02 AM

Who needs the Great Wall of China and Chichen Itza? Wisconsin is full of wonders that are much closer to home. So pack up the car, fire up the GPS and get ready to crisscross America's Dairyland with OnMilwaukee.com as we travel to the Seven Wonders of Wisconsin this summer.

BARABOO – It is a haven for outdoors enthusiasts, swimmers, hikers, campers, rock climbers and those looking to just get away from it all for a day. It's also a geological marvel.

Like many of the most famous natural features of Wisconsin, Devil's Lake and the surrounding area is the result of glacial activity.

The bluffs surrounding Devil's Lake are part of the Baraboo Hills, an oval-shaped range stretching 25 miles wide and 10 miles long, centered around Baraboo.

In prehistoric times, the hills were part of a massive mountain range and through millions of years, have been weathered by the effects of erosion. Today, the remaining rocks – mostly Baraboo Quartzite – are among the oldest exposed rocks in North America at approximately 1.8 million years old.

Geologists aren't exactly sure how the lake was created but the most popular theory is that the ancient Wisconsin River at one time flowed through the gorge and was eventually blocked by glaciers, which pushed their way into the area from the north and east.

The glaciers' halt left two large terminal moraines along the north and south ends of the park, trapping the river, geologists say, between the bluffs and creating what we today know as Devil's Lake, a 360-acre spring-fed body of water that has been captivating visitors for generations.

Today, Devil's Lake is the centerpiece of Wisconsin's largest and most popular state park, encompassing approximately 10,000 acres surrounding the endorheic lake and attracting approximately 1.8 million visitors per year.

The area had long been a popular destination for tourists, even before the state established it as an official park – and long before the upper Midwest was visited by the first European explorers.

Evidence suggests that prehistoric people used portions of the area for shelters nearly 10,000 years ago with mound-building Native Americans arriving about 1,000 years ago. A number of effigy mounds remain in the park today.

The first non-Native American to visit the park is believed to be John De La Ronde in 1832, and naturalist Increase Lapham noted "a large body of broken fragments have accumulated along the edge of the water" in 1849.

The first hotels and resorts began appearing on the property in the 1860s and Devil's Lake became even more popular when the first rail line was completed in 1873. Those early resorts catered to the upper class, who arrived by train from Chicago, Milwaukee and Minneapolis.

That's when things really took off, says park superintendent Steve Schmelzer, who has been at Devil's Lake since 1992. "We're situated halfway between Chicago and Minneapolis, so it was kind of a natural stopping point. There was a train station here and once the trains started coming in, hotels started popping up around the lake to cater to the people coming through."

As the 19th century came to a close, the first calls for preservation went up amongst locals who watched as the growing crowds started to threaten the area's natural beauty.

After the first Wisconsin State Park, Interstate, in St. Croix Falls, was established in 1900, landscape architect John Nolan was hired to draft a comprehensive plan for the state's park system. Devil's Lake was among the four original recommended areas, along with what would become Peninsula State Park in Door County, Wyalusing State Park near Prairie du Chien and the Dells of the Wisconsin River which later became a state natural area.

"There was a push from the local community in about 1903 to make it a state park," says Schmelzer. "In 1906, they had the support of local legislators but in the last vote, it didn't pass because some Door County legislators thought Door County should be the spot for the next park."

After years of political maneuvering, Devil's Lake officially became a State Park in 1911. Less than 10 years later, annual attendance surpassed the 100,000 mark and by 1924, more than 200,000 people were visiting each year to take in the scenery, camp and even enjoy big band concerts and dances.

The crowds kept coming even as the Great Depression ravaged the country. As part of Franklin Delano Roosevelt's New Deal, a Civilian Conservation Corps camp was established at the park and from 1934-1941, approximately 200 men helped to build trails, buildings and other park facilities, many of which are still used today.

"They did a lot of work here," Schmelzer says. "The headquarters building is a CCC building along with a couple shower buildings, restroom facilities and the law enforcement building. The walls you see when you drive into the park ... they did those, too."

The post-war boom brought record crowds an attendance was well over one million by the 1950s. To accommodate the growing number of visitors, the park underwent a number of upgrades.

A nine-hole golf course on the north end was removed and the Quartzite Campground was created. Another new campground was built in the mid-'80s and presently, there are 407 campsites in the park, most of which fill up quickly during the summer.

The park's popularity has a lot to do with the wide range of activities available to visitors. Along with swimming and camping, there are roughly 30 miles of hiking or bike trails ranging in difficulty. Rock climbers are a regular sight scaling the bluffs and scuba divers can take advantage of the lake's clear visibility and still waters.

"It's so close to Milwaukee, Madison and Chicago so (the park) gets a lot of use," Schmelzer says. "People come here to do a lot of different things. We've got probably the busiest hiking trails in the state of Wisconsin. The Tumbled Rocks Trail, which goes along the lake and then the East and West Bluff Trails, those are some of the only blacktop trails you'll find just because of the sheer amount of use they get."

Because of its popularity, just getting into the park can be difficult during summer weekends, when the line of cars often stretches from the park office all the way out to the highway.

"Our parking lots fill up fast sometimes," Schmelzer says. "If you come during the week, though, when it's not as busy, there's still plenty to do."

The park celebrates its centennial this year and will mark the occasion formally with a ceremony June 25 on the north shore.