Cowles Bog is a 4,000-year-old wetland complex in Indiana Dunes National Park, near Chesterton, Indiana. It is named for Henry Chandler Cowles who did his pioneering work in ecology and ecological succession here. His work brought international attention to the area which led to efforts to preserve the Indiana Dunes. It was designated a National Natural Landmark in 1965. It contains bog, fen, marsh, wet meadow, swamp, and pond habitats.