Harwich is a New England town on Cape Cod, in Barnstable County in the state of Massachusetts in the United States. At the 2020 census it had a population of 13,440. Harwich experiences a seasonal increase to roughly 37,000. The town is a popular vacation spot, located near the Cape Cod National Seashore. Harwich's beaches are on the Nantucket Sound side of Cape Cod. Harwich has three active harbors. Saquatucket, Wychmere and Allen Harbors are all in Harwich Port.