Black Moshannon State Park is not worth the trip or effort.
Swimming is a joke, restrooms are old and filthy, picnic tables and grills are old, dangerous and filthy. Fishing is rotten to say the least.
Cabins for rent are old without any amenities (including electricity) which is fine except for the price of such old cabins. They also are filthy.
There is not a motel around or any restaurants within 35 miles, so be prepared. I am usually not this critical of a state park but Black Moshannon is one of the worst. Expect most areas to be closed on and off all summer without any explanation. Expect unkept camping grounds and just yuck everywhere.
There are no nature trails. It is a depressing experience.