Harmonic constants for tidal sea level fluctuations in the Keret Bay of the Kandalaksha Gulf of the White Sea are once again calculated. Here, at the inflow of Keret bay waters and those of the river with the same name, on the island Sredny, the Marine Biological Station of St. Petersburg State University (MBS of SPbSU) and educational units of biological faculty of the Kazan (Volga) federal university (KFU) and the Oceanology department of SPbSU are located. In the Keret Bay and adjacent water areas intensive scientific work of biological, ecological, hydrological and oceanographic directions is carried out. It is obvious that the tidal phenomena make an essential contribution to all processes happening in the Keret Bay, and, therefore, for carrying out any research and while organizing field works it is necessary to know main characteristics of tide and have opportunity to predict tidal conditions on this or that interval of time. By monthly series of hourly in situ supervision over the sea level with the help of the method of the least squares the amplitudes and phases of 33 components of tide of which 2 - long-period harmonicas, 7 diurnal, 6 semidiurnal and 18 shallow water harmonicas, were calculated. New harmonic constants obtained describe 97% of variance of the measured sea level. They can be used for calculations of tides at any interval of time of the summer period of field works with more exact predictions than before.