Abstract: An aerodynamic and hydromechanical hydroplaning disc with a solid unitary body comprised of aggregated material. The disc is heavier than the water it displaces and non-floating. A series of longitudinally oriented (i.e., meridionally oriented, or north-south) discontinuities are provided only on the extreme latitudinal periphery of the rim adjacent to the top and bottom surfaces of the disc. Said discontinuities: exert a greater interfering effect on the airflow and waterflow around the circumference than over the top and under the bottom surfaces; create a turbulent, separated and unseparated, peripheral boundary layer in air and water; reduce air resistance and water resistance; increase range, frequency of skips, and dynamic stability. Also, there is provided a granular texture on the bottom and circumferential surfaces of the disc which results in a more sure grip and improved hydroplaning stability (i.e., the ability of the disc to maintain a horizontal orientation while hydroplaning).