Abstract: An adjustable fin insert assembly is disclosed for mounting on a cavity of a wake board, and includes a fin box positionable in the cavity of the board. The fin box is elongate and includes a longitudinal slot which extends into the fin box from a lower surface thereof. The assembly includes a fin member removably mountable on the fin box adjacent the slot with a portion of the fin member extending into and being slidable along the slot for permitting adjustment of a position of the fin member in the slot. The assembly also includes a plurality of positioning members positioned in the slot and being longitudinally slidable in the slot. A space is defined in the slot adjacent to at least one of the positioning members, and the space is repositionable in the slot by sliding the at least one of the positioning members.