If you're looking for a unique spot to go fishing in Pennsylvania this summer, look no further than Lake Grubb in Lancaster County. Lake Grubb has firmly established itself as a Pennsylvania gem located between Harrisburg and Philadelphia, and the small body of water is an old iron ore mine that eventually filled with pristine water. Before the quarry closed, miners struck an underground spring beneath the iron pit. Lake Grubb turned into a private club in the 1930s, which was active until 1955. Now known as Lake Grubb Nature Park, a 54-acre wooded park around the lake, followed three years later.