Abstract: A bottom moored and tethered directional frequency analysis and ranging (DIFAR) sensor system deployable in a wide range of water depths. The system includes a mooring platform for anchoring the system to the bottom surface of a body of water. A buoyant chamber containing a DIFAR sensor is tethered to the mooring platform at a pre-determined depth in the body of water. The DIFAR sensor includes two pairs of orthogonally oriented hydrophones and a compass for providing a directional magnetic reference signal. The tethered buoyant chamber is securely positioned such that hydrophones residing within the buoyant chamber are oriented in a plane substantially co-planer to the top surface of the body of water. By determining the angle between the directional magnetic reference signal and the hydrophones, the sensor system is able to compute heading information for a detected object. A transmitter is coupled to the DIFAR sensor for transmitting heading information detected by the DIFAR sensor to a receiver.