This presentation explores semantics as an enabling technology to solve the daunting security problems of preparation and response as applied to Maritime Domain Awareness (MDA). Maritime Security depends upon the fusion of intelligence across thousands of diverse organizations(International, Federal, State, Local, and Commercial), processing large volumes of information, and interconnecting multitudes of sensors and systems. Traditional methods for interoperability and data exchange will not achieve the desired coordination between agencies, especially to prevent and/or respond to a major incident (natural disaster or terrorist attack). Ontologies, machine-processable semantics, will be examined for their ability to solve interoperability problems and provide predictive analytics for MDA missions. Additionally, management and development of the semantic web and MDA semantic layers will be discussed.