concrete block tetrapod for breakwater and wave water dissipating prevent erosion at fishery fishing jetty in east japan sea and

anchor barricade barrier bay beach block break breakwater cement city coast coastal coastline concrete construction destination dissipating east erosion fishery fishing gyeongsang gyeongsangbuk harbor idyllic island japan jetty korea korean landmark massive north ocean pier pod pohang port prevent prevention protect protection quay rock safety sand scenery scenic sea seaside seawall shore sightseeing south stone strong structure tetrapod travel wall water wave