Brown's Lake Bog is a protected nature preserve in southwestern Wayne County, Ohio, near Shreve. Owned by The Nature Conservancy and dedicated as an Ohio state nature preserve, it is open to the public. It is significant as one of the few remaining kettle peatlands in Ohio and preserves an unusually intact wetland formed by glacial activity. Its features include a kettle lake, a kame, and a floating sphagnum moss mat. In 1967, Brown's Lake Bog received national recognition when it was designated a National Natural Landmark.