The acoustic wave gauge was developed by the Institute of Applied Physics of the Russian Academy of Sciences (IAP RAS) for long-term all-weather monitoring of wind waves. The instrument can be used to validate remote sensing data. Currently the instrument is being tested in various conditions and compared with different buoys. The acoustic wave gauge “Kalmar” was installed at the Gelendzhik test site of the Southern Branch of the Shirshov Institute of Oceanology RAS (IO RAS) in 2019 and has worked successfully till December of 2020. The ADCP RDI WH-600 device was also installed at the landfill. Both instruments are installed underwater and use ultrasound to scan the water surface, they are able to measure omnidirectuinal wave spectrum. The parameters of large waves (up to 12 m) can be calculated from the measured wave spectrum. In the paper both the wave spectra themselves and the significant wave heights are compared for February 1–10, 2020. It is shown that the wave heights measured by the two instruments are close and the difference between the measurements of the acoustic wave gauge and the results of two different ADCP data processing algorithms (Echo and Velocity) do not differ more than the results of the two algorithms differ from each other. The spectra measured by the two instruments differ in the peak region, and fall off in the same way. However, the spectra recovered by different methods from ADCP measurements also differ, so that the shape of the recovered spectrum depends significantly on the processing algorithm. In the future, it is planned to consider this issue in more detail and compare the measurements of the acoustic altimeter with the measurements of the string wave gauge.