St Mawes is a village on the end of the Roseland Peninsula, in the eastern side of Falmouth harbour, on the south coast of Cornwall, England. The village, formerly two separate hamlets, lies on the east bank of the Carrick Roads, a large waterway created after the Ice Age from an ancient valley which flooded as the melt waters caused the sea level to rise. The immense natural harbour thus created is claimed to be the third largest in the world.