A wave measuring buoy for measuring ocean surface wave amplitude, frequency and direction of propagation is disclosed. The buoy includes a single-axis accelerometer suspended as a pendulum inside a water-proof housing. The water-proof housing is connected to and beneath the flotation hull of the buoy and is located at the center of rotation of the buoy assembly so that the accelerometer is substantially insensitive to roll and pitch motions of the buoy. An inclinometer and a compass are fixedly mounted inside of said flotation hull. Inasmuch as the inclinometer is fixed in the water-proof housing it responds to the pitch and roll motions of the buoy and the compass indicates the direction of said roll and pitch. The output of the accelerometer is an analog signal proportional to the vertical (heave) acceleration of the buoy. The outputs of the inclinometer and the compass are analog signals which indicate the pitch and roll of the buoy and the magnetic heading of said pitch and roll. The analog signal of the accelerometer is correlated with the pitch and roll signal of the inclinometer and the bearing signal of the compass to indicate the direction of the wave propagation. A frequency transfer calibration can be applied to the accelerometer output to compensate for the mass, size and resonant heave behavior of the buoy.