Falmouth, Massachusetts. Falmouth (pronunciation: /ˈfælmᵻθ/ FAL-mith) is a town in Barnstable County, Massachusetts, United States; Barnstable County is coextensive with Cape Cod. The population was 31,532 at the 2010 census, making Falmouth the second-largest municipality on Cape Cod after Barnstable. The terminal for the Steamship Authority ferries to Martha's Vineyard is located in the village of Woods Hole in Falmouth.