The rising importance of Unmanned Surface Vessels (USVs) in diverse maritime contexts, such as coastal monitoring and oceanographic applications, underscores the necessity for a robust simulation environment framework. This need arises from the limited availability of sea trials and demands a high-quality simulation setup to test USV autonomy across multiple scenarios with enhanced visual fidelity. This paper describes an autonomous navigation framework for USV in a Marine Robotics Unity Simulator (MARUS), a high-fidelity simulation environment based on Unity3D to close the gap. Our approach works on coupling the MARUS simulator offering water physics and a wide array of sensors commonly used in the maritime domain with a Robot Operating System (ROS) to facilitate remotely controlled USV behaviour and motion for different navigation scenarios to assess the vessel's maneuverability and overall performance characteristics.