Existing maritime navigation and reconnaissance systems require man-in-the-loop situation awareness for obstacle avoidance, area survey analysis, threat assessment, and mission re-planning. We have developed a boat with fully autonomous navigation, surveillance, and reactive behaviors. Autonomous water navigation is achieved with no prior maps or other data − the water surface, riverbanks obstacles, movers and salient objects are discovered and mapped in real-time using a circular array of cameras along with a self-directed pan-tilt camera. The autonomous boat has been tested on harbor and river domains. Results of the detection, tracking, mapping and navigation will be presented.