Abstract: There is an enormous need for advanced technology in Sri Lanka, with the need to raise an alert immediately to the lifeguards and swimmers nearby in case a person crosses into dangerous deep-water zones. This paper presents the development of a novel sensor-based system capable of detecting and warning lifeguards whenever a person enters unsafe zones in the water. It detects objects on the water surface by use of ultrasonic sensors and passive infrared sensors that help tell if the detected object is a living being or not by checking on the heat signature. It runs on a rechargeable battery and a solar panel, making it efficient and self-sustaining. Testing detected that during the day, the maximum range of system detection was 3.5 meters, while at night it was 4 meters with rates of 79% and 86%, respectively. These results indicate that this sensor-based system would increase water safety through real-time alerts, hence reducing drowning-related fatalities, and probable future improvements with better sensors in order to enhance the accuracy and detection range of the system.