We present results of observations of internal waves (IW) on the river plumes caused by the spread of the front of fresh waters, based on satellite images of the visible range obtained by Sentinel-2A Multispectral Imager Instrument (MSI/S2) and Landsat-8 Operational Land Imager (OLI/L8) instruments. Due to the high spatial resolution of these satellite data, submesoscale IWs having wavelengths less than 50 m and generated by unstable sharp front of a river plume, were revealed and their parameters were assessed. The plumes of the following rivers were studied: the Rhone, flowing into the Gulf of Lyon of the Mediterranean Sea, the Danube, flowing into the northwestern part of the Black Sea and the Coruh flowing into the southeastern part of the Black Sea. We discuss spatio-temporal variability of the manifestations of internal waves of a given type mechanisms of their generation.