NOVELTY - The subsurface wave action harnessing system comprises a seabed mounting plate (30) for securing to a seabed, a wing (20) having opposed first and second wing surfaces extending between a first wing end and a second wing end, a drive arm (16) pivotably connected to the wing to convert the pivoting motion into reciprocal motion, a wing directional plate (34) rotatably mounted to the seabed mounting plate, a wing mounting rail (36) arranged on the seabed mounting plate, a water purification assembly driven by the drive arm, and a turbine disposed within the fluid chamber.    USE - The subsurface wave action harnessing system is useful in a wave action-driven water purification system (claimed).    ADVANTAGE - The system is capable of consistently and rapidly harnessing a subsurface wave action thus easily purifying the water with less power consumption and without any environmental impact, and prevents or minimizes the damage during the periods of high subsurface wave action.    DETAILED DESCRIPTION - The subsurface wave action harnessing system comprises a seabed mounting plate (30) for securing to a seabed, a wing (20) having opposed first and second wing surfaces extending between a first wing end and a second wing end, a drive arm (16) pivotably connected to the wing to convert the pivoting motion into reciprocal motion, a wing directional plate (34) rotatably mounted to the seabed mounting plate, a wing mounting rail (36) arranged on the seabed mounting plate, a water purification assembly driven by the drive arm, a turbine disposed within the fluid chamber and connected to an electrical generator, and an electrical generator driven by the drive arm. The second wing end is pivotably mounted to the seabed mounting plate such that pivoting motion (24) about a pivot axis parallel to the mounting plate is imparted to the wing by subsurface wave action acting on the first and second wing surfaces. The wing is pivotably connected to the seabed mounting plate via the rotating direction plate such that the wing is rotatable about a rotation axis perpendicular to the seabed mounting plate. The wing is slidably and pivotably connected to the seabed mounting plate via the wing mounting rail. The wing includes selectively operable louvers permitting water flow through the wing. The louvers are automatically controlled to open and close based upon sea conditions. The wing is adapted to be selectively locked down to the seabed mounting plate. The water purification assembly includes a fluid chamber having a fluid chamber inlet and an outlet, a piston displaceable within the fluid chamber, and a reverse osmosis assembly connected to the fluid chamber outlet. The drive arm is connected to the piston and operable to reciprocally displace the piston within the fluid chamber to supply pressurized water to the reverse osmosis assembly. INDEPENDENT CLAIMS are included for:    (1) a wave action-driven water purification system; and    (2) a method for harnessing subsurface wave action.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic top view of a subsurface wave action harnessing system.    Drive arm (16)    Wing (20)    Pivoting motion (24)    Seabed mounting plate (30)    Wing directional plate (34)    Wing mounting rail. (36)