The disadvantage of the ultrasonic wave gauges is that they often fail to measure rough seas when water surface is disturbed by strong winds and breaking waves.
A possible measure to overcome such disadvantage is the simultaneous operation of a pressure gauge as an auxiliary wave gauge.
　In this report, two methods are utilized to recover the characteristic wave parameters from pressure records. The one is the conventional method which estimate the characteristic wave parameters on the basis of the linear wave theory and a correction factor. The other is a linear numerical filter which recovers the time series surface wave from pressure records.
　The reliability of the two methods are examined for the simultaneous time series records of the surface and the pressure attained at Naha Port (water depth 50m)
and Hitachinaka Port (30 m). The results show that the linear numerical filter is quite reliable and suitable for real-time surface wave recovery during storm waves.