DC power distribution system is being considered as an attractive alternative to its traditional AC counterpart in many fields of applications and, in particular, for maritime onboard power systems. The adoption of DC power architecture would bring a broad range of benefits to the onboard power system. Not only frequency-related constraints are eliminated, which allows high-speed smaller generators to be used, but also new fault-tolerant configurations involving power electronics, generation control, as well as smart systemic management. For these reasons, DC power systems become natural alternative to the conventional AC power systems in the field of future maritime applications. Moreover, the inevitable cabin structure of maritime applications naturally separate the large-scale power system into several zonal parts. Furthermore, it is expected that the zonal parts can maintain autonomous power supply for a short time, which make the system highly consist with DC microgrids. In this content, it is foreseeable that the advanced research outcomes in the field of DC microgrid are also compatible with maritime onboard power systems. In this paper, DC power architectures, control and coordination methods, and specific issues of maritime onboard power system, fuel efficiency optimization and systemic reconfiguration are outlined, referring to state-of-the-art realizations as well as to novel concept designs presently under development and investigation.