The Helford River (Cornish: Dowr Mahonyer) is a ria (flooded river valley) in Cornwall, England, United Kingdom. It is fed by a number of small streams into its many creeks. There are seven creeks on the Helford; from west to east these are Ponsontuel Creek, Mawgan Creek, Polpenwith Creek, Polwheveral Creek, Frenchman's Creek, Port Navas Creek, and Gillan Creek, the best known of which is Frenchman's Creek, made famous by Daphne du Maurier in her novel of the same name.