The state park, established in 1923 and opened in 1926, comprises 3.4 square miles (8.8 square km) of shoreline, marshland, dunes, and forests near Chesterton. In addition to a 3-mile (5-km) sandy beach, it has facilities for camping, picnicking, fishing, and hiking. An outstanding feature is the Big Blowout in the east end of the park, where lake winds have exposed a “tree graveyard” created by sands constantly drifting over a wooded area. Shifting dunes, such as Mount Tom, may reach heights of almost 200 feet (60 metres). Mount Baldy, 125 feet (38 metres) high, is moving inland at a rate of some 4 feet (1.2 metres) per year.

The authorization of the national lakeshore in 1966 was the culmination of a 50-year fight to save the dunes from the encroachment of industrialization. It provided for the acquisition of 13 square miles (34 square km) of dunes and wetland. The national lakeshore—which is on a bird migration route and contains the state park on its three land sides—features long sandy beaches, high dunes, deep swales, wooded ravines, prairie remnants, and interdunal ponds and swamps; it also includes fens and bogs that are remnants of Ice Age glaciers. In the dunes is found a highly diverse flora ranging widely in climatic type from Arctic bearberry to tropical orchids and from wetlands loosestrife to desert cactus. The Bailly Homestead (1822) and the Chellberg Farm (1872) are preserved as historical sites. Botanist Henry Chandler Cowles (Cowles, Henry Chandler) formulated the concept of ecological succession after studying the dunes in the 1890s. Since the 1970s, further duneland has been acquired through the efforts of conservation groups, increasing the total combined area of the national lakeshore and the state park to 24 square miles (62 square km). It includes nearby Hoosier Prairie, Hobart Prairie Grove, Heron Rookery, and Pinhook Bog.