Falmouth (fălˈməth) [key], town (1991 pop. 17,810), Cornwall, SW England, on a small peninsula between Falmouth Bay and Carrick Roads estuary. Falmouth is a port, a resort, and the headquarters of the Royal Cornwall Yacht Club; there is a maritime museum in the harbor. China clay is exported from the port. Industries include engineering, ship repairing, and oyster fisheries. The climate is unusually warm; subtropical plants thrive. The harbor entrance is guarded by Pendennis Castle on the west and St. Mawes Castle on the east (both 16th cent.). Baron Fairfax of Cameron took the town in 1646 after a five-month siege of Pendennis Castle in the English civil war. The fall of the castle signaled the defeat of the royalists in Cornwall and the end of the civil war there.