The Indiana Dunes are a relatively young creation. As the last Ice Age ended and the glaciers retreated, Lake Michigan rose and fell through several dramatic stages, depositing sandy shorelines at elevations now well inland from the present coast. Today's lake waves and currents continue the process, pushing sand ashore from beds beneath the surface. Wind does the rest, sculpting the deposits into the towering formations that give the park its name. The result is a landscape in constant motion, where dunes migrate, swales flood, and forest slowly colonizes bare sand. Paper birches on the Cowles Bog Trail represent the farthest-south naturally reproducing population of that species in the Great Lakes area. In August, swimmers pack the beaches; in February, the same shoreline bristles with majestic, dangerous shelves of pack ice.

The dunes nearly vanished under steel mills. After U.S. Steel began constructing a massive complex at Gary, Indiana, in the early 1900s, preservation advocates fought back. The National Park Service proposed protecting the duneland as Sand Dunes National Park in 1916, but local opposition killed the idea. Indiana salvaged 2,182 acres as a state park in the 1920s. Then came World War II and the Cold War, and the southern shore of Lake Michigan, with its cheap access to coal and iron ore, became prime real estate for steelmaking. Additional mills were sited within the dunes through the 1950s and early 1960s. It was the construction of Bethlehem Steel's Burns Harbor mill in 1962-64 that finally triggered a public outcry. Senator Paul Douglas of Illinois led the charge, and Congress created the Indiana Dunes National Lakeshore in 1966. In 2019, the lakeshore was reclassified and renamed a national park, Indiana's first.

Because the park was established after heavy industrial and residential development had already claimed much of the dry, buildable land along the shore, it exists as a patchwork of eight separate beachfront parcels and numerous inland tracts. Many of the inland sections are riverbottoms and sandy wetlands, ecosystems less attractive to developers but rich in biological diversity. The roughly 15,000-acre park wraps around steel mills, power plants, and small communities like Ogden Dunes, Dune Acres, and Beverly Shores. The juxtaposition can be startling. A swimmer on Central Beach gazes at deep blue water and golden sand while a coal-fired power plant looms to the east. But for visitors willing to embrace the contrast, the Indiana Dunes offer something no pristine wilderness can: proof that wild beauty and heavy industry can share the same horizon.

Sitting at the southern tip of Lake Michigan, the Indiana Dunes form a natural bottleneck on the continent's great migration flyways. Over 300 bird species have been recorded living in or passing through the park, with the greatest concentrations during the spring migration in April and May and the autumn passage from September through October. The Inland Marsh Overlook, accessed by a short boardwalk trail between two tree-covered dunes, offers wheelchair-accessible views of a vast wetland where flocks of Arctic-nesting shorebirds pause alongside tropical warblers. Black-eyed Susans and goldenrod carpet the prairies in summer. Whitetail deer browse the woodlands in quantity, and beavers, muskrats, and squirrels are easily spotted along the Little Calumet River. The Bailly-Chellberg farm, established by fur trader Joseph Bailly on the river's banks in 1822, still operates a maple-syrup boil each early spring.

One of the park's great advantages is accessibility. The South Shore Line commuter rail runs from downtown Chicago directly through the dunes, with stations at Dune Park and Portage/Ogden Dunes. Roughly a dozen trains pass each way on weekdays. From Dune Park station, a 20-minute sidewalk walk leads to the main entrance of Indiana Dunes State Park, which operates separately with its own admission fee inside the national park's boundaries. Interstate highways connect the dunes to Indianapolis, Detroit, and Cleveland. For those arriving by air, the park sits roughly equidistant between Chicago's two major airports. The beaches grow less crowded as you move east from Chicago, and the easternmost stretches at Central Beach and Mt. Baldy offer the most solitude.