Native Americans who used the island as a hunting ground carved symbols into this boulder on the island's south shore sometime between AD 1200 and 1600. You can see the rock via a viewing platform.
It's not known who, exactly, made the petroglyphs. Historians believe they're the work of either the Late Prehistoric Period Sandusky culture, or the Erie, Cat, Neutral or other indigenous peoples living in the region when Europeans arrived.