The intent of this paper is to introduce a monitoring system for the instantaneous velocity measurements of swimming movements, aiming to provide useful data representation to be used by coaches to analyze the athletes' performance. The basis of the system is using a video monitoring system to record the underwater movements during actual performance of the swimmer and analyze them through numerical data graphical representation of the velocity. The swimmers instantaneous velocity is evaluated versus the swimming movements, this combination gives a clearer and detailed figure of the swimming movements on a timely manner, enabling the identification of the points of strength and weakness in the athletes' performance.