Shikellamy State Park is a 132-acre (53 ha) Pennsylvania state park located at the confluence of the West Branch Susquehanna River and Susquehanna River in Pennsylvania in the United States. The park is divided into two sections. The older part, on a bluff on the western bank of the river, is the 78-acre (32 ha) Shikellamy overlook in Union Township, Union County. The newer part is the 54-acre (22 ha) marina on the southern end of Packer Island in Upper Augusta Township, Northumberland County. Packer's Island lies between the city of Sunbury and the borough of Northumberland at the confluence of the two branches of the river.