Grand Lake St. Marys State Park

Originally constructed as a feeder reservoir for the Miami-Erie Canal, Grand Lake St. Marys was for many years recognized as the largest man-made reservoir in the world. The 13,500-acre lake is the gateway to swimming, boating, camping in a 198 site campground and fishing in one of Ohio's oldest state parks. Camping Hiking Swimming Boating Fishing Horseshoes Volleyball Nature Programs Pet Friendly Cabin