[2] The park is broken into two units that encompass an area of 4,160 acres (1,683 ha) and contains over six miles of Lake Michigan shoreline.

Recreational activities at the park include boating, swimming, hiking, bicycling, camping, bird watching, and picnicking.

[3] Known primarily for the beach, the park also includes dune areas, wetlands, prairie, and black oak savanna.

This erosion and subsequent accretion process created the characteristically curved ridges and swales of the park as the complex migrates south.

[6] The northern unit of Illinois Beach State Park experiences rapid rates of erosion, which was exacerbated by the construction of North Point Marina in 1989 and reaches highs of 60 ft per year.