A locking device for a watersports apparatus which in one embodiment, comprises a pair of interlocking brackets which form an inverted "T" when slidably disposed in a channel associated with a fin box. Apertures are provided to allow a cable or other security device to traverse the inverted "T" locking device for securing the watersports apparatus. In a second embodiment, a pair of generally planar scissor members having a pair of unguiform clasping elements aligned in opposition and configured to clasp a rod disposed in a tether plug aperture by scissor action. Useful watersport tools may be provided on the distal ends of the generally planar scissor members. The useful tools include a screwdriver, a wax comb, a bottle cap opener and a wax scrapper.