This thesis is focused on possibility of constructing distributed underwater sonar which has an ability to increase or decrease number of sensor elements without any modification on its hardware. Each sonar module works individually. Its synchronization and communication between modules and the image processing unit are archived by using CAN protocol. This new design concept gives several advantages over conventional design.Only one prototype was made, but several modules must be combined in the actual application. The discussion about a complete system can be found in the future work section.The project composes of two main parts: design and building a prototype. The testing procedure and result of both parts are described and summarized with a conclusion.