Discover rich history and great recreation at Grand Lake St. Marys. This region was a key link between the Great Lakes and the Ohio River, vital in opening the Northwest Territory. Originally built as a feeder reservoir for the Miami & Erie Canal, it was once the world’s largest artificial reservoir. Hosting the world’s first offshore oil drilling site in 1891, the park now offers 52 miles of shoreline for boating and fishing, along with a campground, picnic areas, and a swimming pool. Dive into a captivating blend of history and leisure!