In history, concurrence for dominance at sea has always been a major concern for most sea-facing countries. As the vast majority of worldwide goods exchanges are made by sea, an answer to the growth of the worldwide commerce over the last twenty years has been to increase the size and on board value of ships sailing between eastern and western countries. Digitalization has also been an answer to ease the routing, management, conning and overall return on investment of such ships. But as the cyber surface attacks consequently widened, the maritime sector became a real interest for state-sponsored and criminal hackers. The concern of a major cyberattack targeting ships at sea or naval shore infrastructures is no more science ction, and late incidents do conrm the urgency to act. "Safety is paramount" is a known motto on board ships, the crew being drilled for re and water oods. However, the awareness of the sector on cyber remains low and if modern ships have a reduced crew, autonomous ships are arriving with just nobody on board. This is the reason why, on top of the usual cyber-security measures, the implementation of intrusion detection systems on unmanned vehicles is essential to detect, react and stop any incoming threat. In this paper, we outline the main challenges for the years to come on Maritime Cyber Situational Awareness (MCSA) for autonomous and remotely controlled vehicles.