Abstract: A swim fin having a foot portion and a blade portion. The blade portion includes a plurality of transversely spaced longitudinally extending ribs that are connected to each other by a web member. The ribs are comprised of a plurality of elongated flexible members juxtaposed upon each other with the elongated members being inherently biased to a relatively straight condition interlocking tangs and grooves on the juxtaposed elongated members prevent lateral separation of the members. A pin passing transversely through the elongated members acts to limit the longitudinal displacement of one elongated member with respect to another.