A method for harnessing wave energy includes providing a vehicle to a body of water, the vehicle. The method includes submerging the vehicle to a depth in the body of water. The method includes operating the motor-generator of the vehicle in the first quadrant of the motor-generator. The method includes detecting a phase of a wave in the body of water based information from the processor of the detected phase. The method includes orienting the vehicle to lag the phase of the wave based on the detected phase of the wave. The method includes synchronizing an inertial acceleration of the vehicle to movement of the wave. The method includes switching the motor-generator to the second quadrant for generation mode to convert energy from the movement of the wave to electrical energy. The method includes storing the energy from the wave in the rechargeable battery source.