Canfield Island Site is a prehistoric Native American archaeological site on an artificial island in the West Branch Susquehanna River east of Williamsport, Pennsylvania. Though only 21 acres, it preserves an unusually deep record, with artifacts found as much as 15 metres below the surface. Investigations beginning in 1958 and major excavations from 1960 to 1980 revealed occupation from more than one millennium before Christ through the Late Archaic, multiple Woodland phases, and into the time of the Susquehannock. Massive hearths and many fishing nets suggest the island was once a major fishery, and its long sequence has made it especially valuable for dating comparisons across Pennsylvania.