Abstract: We present the concept of a new experimental Sediment Sonar System and preliminary results from the first sea trials. The planar (2-dim) array produces 3-dimensional images of the upper sediment layer. These can be used for detection and classification of buried objects by means of image processing methods. Since the system is ship mounted, it provides a high degree of flexibility with respect to search rate, target/bottom type selection and aspect angle diversity. Besides the classification of objects in different environments the system allows the application and investigation of new signal processing methods like motion compensation, autofocus and synthetic aperture. During the first sea trials, several objects like spheres and cylinders as well as exercise mines were analyzed. Preliminary examples are shown.