Abstract. Modeling of the Black Sea and Caspian Sea waters dynamics was conducted within the framework of the European ECOOP project and Russian project JISWO on the basis of the Princeton Ocean Model (POM). Nowcasting and tree days forecasting of the Black Sea dynamics was carried out in a daily mode with horizontal resolution of ∼1 km along the Russian coast of the basin. The nowcasting of the Caspian Sea dynamics was carried out every ten days with horizontal resolution of ∼5 km on the basis of climatic information about water temperature and salinity and decade-averaged wind NCEP-NCAR. Examples of calculations are presented here and their comparison with space remote sensing and in situ (hydrological measurements) data is fulfilled, and the results of model validation are discussed.