Almost everything about Pymatuning State Park is huge. At 21,122 acres, it is one of the largest state parks in the Commonwealth. The 17,088-acre Pymatuning Reservoir is the largest lake in the Commonwealth. In its three campgrounds, Pymatuning has the most campsites in the Pennsylvania state park system. More people visit Pymatuning than almost any other state park in Pennsylvania. But the biggest thing about Pymatuning is the fun you can have boating, fishing, swimming, camping and enjoying other recreational opportunities.