In this study, the cooling and freezing processes of pooled water to the point of release of supercooling have been investigated both experimentally and numerically. Pure water in double horizontal concentric cylinders is cooled, varying the cooling rate. In the experiment, the time-dependent sequential flow and temperature fields are visualized and measured using a real-time holographic interferometry technique coupled with a speckle photography one. The nurerical calculation is made under the condition of the same cooling rates as obtained in the experiment in order to verify the validity of the experimental results. It is clarified that a cooling rate influences the supercooling characteristics and its relation to the ice formation appeared just after the release of supercooling.