Pymatuning State Park is Pennsylvania state park covering 21,122 acres (8,548 ha) in Conneaut, North Shenango, Pine, Sadsbury, South Shenango, West Fallowfield and West Shenango Townships, Crawford County, Pennsylvania, in the United States. Pymatuning State Park is the largest state park in Pennsylvania and contains the 17,088 acres (6,915 ha) of Pymatuning Lake, three-quarters of which is in Pennsylvania and one-quarter of which is in Ohio. A three-mile (5 km) causeway extends between Pennsylvania and Ohio near the center of the lake.
The lake provides fishing and boating year round. There are two natural areas, Clark Island (161 acres (65 ha)) and Blackjack (725 acres (293 ha)) in the park. The park is also home to the University of Pittsburgh's Pymatuning Laboratory of Ecology. Like all Pennsylvania state parks, admission to the Pymatuning State Park is free. The northern access for Pymatuning State Park can be reached from U.S. Route 6 and the southern access is reached from U.S. Route 322.Pymatuning State Park was chosen by the Pennsylvania Department of Conservation and Natural Resources (DCNR) and its Bureau of Parks as one of "Twenty Must-See Pennsylvania State Parks".