Pinhook Bog

Pinhook Bog is a 110-acre quaking bog inside Indiana Dunes National Park’s 580-acre Pinhook unit. It’s one of North America’s southernmost quaking bogs: a mat of sphagnum moss floats over dark water and trembles underfoot. Come for this unusual wetland and its plants, not a long hike.

The 0.9-mile Bog Trail and its floating boardwalk open only during ranger-led summer weekend open houses. Check the park’s program calendar before coming specifically for the bog; you can’t enter the bog on your own. When the bog trail is closed, the separate 2.1-mile Upland Trail is a self-guided, lollipop-shaped loop through beech and maple woods on a glacial moraine. It takes about 1.5 hours, with a view of the bog near the south end; the park recommends hiking it clockwise.

The trailhead is at 957 N. Wozniak Road. Its paved lot has two picnic tables, a seasonal portable toilet, and no potable water. Passes are required. The trails and picnic tables aren’t wheelchair accessible. Dogs on a short leash are allowed on the Upland Trail, but not on the Bog Trail, where they could damage the habitat.

A block of ice left behind as the glaciers retreated melted into a low basin with no outlet. Rain and runoff collect there; as plants die and decay slowly, the water turns acidic—about pH 4, compared with roughly 7–9 in nearby lakes and streams. That chemistry is what lets bog plants thrive here.

The floating bog mat supports 167 native species. Sphagnum moss spreads across it, with pitcher plants and sundews among the insect-eating plants, plus orchids such as pink lady’s slipper. Tamarack and red maple grow around the bog. Different plants bloom at different points from early to late summer, so an open-house weekend can show a different slice of the bog’s color.

The south end of the Upland Trail loop gives you a view across the bog without entering it. If you visit during a ranger-led open house, the floating boardwalk brings you close to the moss mat and its plants. It moves and can submerge underfoot, so the park recommends waterproof boots.

Pinhook Bog became a National Natural Landmark in 1965, and the federal government bought the unit in 1976. The park actively restores the bog: surveys found some rare plants declining as highbush blueberry and red maple spread, so staff remove that growth to let light reach the mat and hand-pollinate pink lady’s slipper.