Growth prospects for ocean economy are promising because ocean industries are addressing challenges such as food security, energy security and climate change. However, safety and efficiency are the general challenges of ocean operations. Increased automation is believed to solve these problems. This paper discusses the impact of automation on safety and efficiency. A literature review of 'Human factors' mainly from the aviation and maritime industries is presented to untangle the human-machine relationship characteristics when increased automation is introduced to operators. A literature review of Hydrodynamics, Guidance, Navigation and Control (GNC) technologies is presented to introduce the state-of-art and associated limitations. It is concluded that, if the industry's drive is safety and efficiency, then full-autonomy is, at present, not the way to go. Remote control, instead, could facilitate a feasible future, while focused research and development are in need.