There's a bike trail in there somewhere.
The Calumet Bike Trail (dirt or crushed limestone) is about 15 miles long, connecting points in the eastern half of Indiana Dunes NL from Cowles Bog to Mount Baldy. This picture is taken from near the Cowles Bog end.
This is a nice illustration of the challenges of this highly-fragmented national park. The bike trail parallels the Dunes Highway and the railroad. The park is interspersed among steel mills, power plants, commercial and residential areas.
Photo taken September 2007.