A B S T R A C TThis paper describes a novel concept for detecting and tracking underwater cables that differs from common detection methods, including visual, acoustic and magnetic detection, which are based on a survey platform, such as remotely operated vehicles and autonomous underwater vehicles, and have high costs and require long-time monitoring. The proposed detection method can be performed in locations that are difficult to observe using cameras without the use of magnetic fields. The concept relies on low-cost flex sensors that provide underwater, realtime, whole cable detection. Building off of this concept, a detection system and an error analysis system were incorporated, which includes the characteristics of the flex sensors, the mounting structure for the flex sensors, and the underwater cable as well as the 2-D cable bend model and a water tank test. The detected data set, which was rendered on an observation monitor, provided visual feedback regarding any bending or warping problems. To evaluate the detection accuracy, mean absolute error and similarity analyses were performed using the observational data and sensor data obtained from the water tank test. The results of these analyses showed strong agreement between the fitted curve to the detected data and the observational curve, indicating acceptable error. These results demonstrate the feasibility of the proposed system for effective underwater cable detection. Thus, the results of this investigation clearly reveal the potential of the novel sensing technique for practical underwater cable detection and monitoring applications. However, the 2-D cable bending detection model is not suitable for 3-D bending or torsion, which will be considered in future research.