Spring Mill State Park
Spring Mill State Park takes its name from the grist mill that operated here in the early 1800s. The Civilian Conservation Corps rebuilt the mill and surrounding village, and that complex is a major attraction in summer and fall. Visit if you like Ė the displays in the mill are especially interesting - but donít expect solitude. For that, or at least a relative degree of solitude, explore the trail system.
Trail 3 is the best in the park; it passes through or by several notable features. Donaldson Woods Nature Preserve, a National Natural Landmark, protects a sixty-seven-acre block of old growth woods, including stands of virgin timber. The preserve name honors an early owner of the property who refused to allow timber cutting. His decision, regarded at the time as eccentric, gave Indiana one of its finest remaining examples of old growth forest. Trail 3 also skirts dozens of sinkholes. Most look like leaf-covered conical depressions in the ground; their sizes vary dramatically. In other places, the ground gives way completely, revealing caves.
During the summer, underground boat tours at Twin Caves venture into the subsurface; if you go, expect to see bats, blind crayfish and perhaps the endangered Northern blind cave fish. Trail 3 also takes you to Donaldson Cave, yet another National Natural Landmark and the site of pioneering studies on underground ecosystems.
Trail 5 is an easy one-mile loop around the lake that is adjacent to the nature center. Expect excellent views, and watch along the lakeshore for the work of beavers. The segment of Trail 4 between the lake and Donaldson Cave is also nice; it follows a stream valley and can be very good for spring wildflowers.