This invention discloses a fin, for use on a surfboard and other watercraft, of a low-drag, high-lift, high-aspect-ratio, low-sweepback-angle planform of symmetrical foil section, with a fit root section that has a forwardly projecting leading edge and cutaway at the trailing edge, alone or in combination with winglets placed on the vertical fin element so as to minimize tip-vortex drag, so as to make the surfboard or watercraft more maneuverable, easier to propel through the water, and to stabilize the surfboard or watercraft.