On the shores of South Carolina's largest lake, Lake Marion, is a South Carolina State Park that is home to a fascinating geologic wonder: massive sinkholes. Known as South Carolina's inland sea, the man-made Lake Marion was formed in 1941 when the Santee River was dammed as part of Santee Cooper's Hydroelectric and Navigation Project. The recreational lake sports a massive 315 miles of shoreline and is one of the 50 largest lakes in America.

In 1942, one year after the lake was formed, the state created Santee State Park, a phenomenal recreational resource within the Palmetto State that, among other things, provides access to beautiful Lake Marion.

The state park is an ideal place for fishing, camping, boating, hiking, canoeing, kayaking and more. It also has the state's only over-water cabins open for the public to rent.

However, one thing you don't hear much about in relation to this park is the massive sinkholes found scattered around the park's 2,500 acres. But take a hike and you'll see them...

The best place to discover many of the sinkholes is on the Sinkhole Pond Nature Trail. The one mile loop trail is clearly marked and leads to the trail's namesake, which is only one of the big sinkholes found in the park.

Sinkhole Pond, like all the other sinkholes found in Santee Park, was created when the shallow layer of limestone on the earth's surface eroded from underneath and then gave way, creating the sinkhole.

Millions of years ago, a very shallow sea covered the area. Limestone deposits were created after the waters receded. However, underneath the limestone it's believed that underwater pools or streams over time eroded away at the underside of the limestone, making it weak and susceptible to cave-ins.

And that is precisely how all of the massive sinkholes formed at Santee State Park.

The park manages intensive efforts to both preserve the sinkholes (for research) and protect the public from the dangers of falling into them. You'll find aesthetically-pleasing fencing surrounding most of them (the pond is an exception), which also helps to identify them. Many have tall overgrowth and aren't as identifiable as others. The fencing will help you scope them out as you hike through the park on the many trails.

One of the sinkholes (shown below) is deeper than a three-story house. It has fully-grown trees sprouting from the bottom and along the inside edges. Still another sinkhole (not shown here) reportedly is a full-fledged cave!

Have you heard about these unusual geologic wonders at Santee State Park — or seem them in person? We'd love to know!

Santee State Park is located at 251 State Park Rd., Santee, SC 29142. The park features two campgrounds with a total of 148 campsites, unique round cabins (10 of them are on a pier over the water), and day use access to launch your watercraft onto Lake Marion. Year-round day-use hours are from 6:00 a.m. to 10:00 p.m. Admission is $2 for adults and $1.25 for seniors. Ages 15 and under are admitted free. Pay at the park office, park store, or at any one of the three green iron ranger boxes located throughout the park. Learn more about Santee State Park on the official website of South Carolina Parks.