Maritime domain awareness (MDA) is defined as the effective understanding of anything associated with the maritime domain that could impact the security, safety, economy, or environment. It is part of a US government interagency and international maritime security effort. The maritime domain is defined as all areas and things of, on, under, relating to, adjacent to, or bordering on a sea, ocean, or other navigable waterway, including all maritime-related activities, infrastructure, people, cargo, and vessels and other conveyances. Maritime Domain Awareness
The Secretary of the Navy is the DoD Executive Agent for maritime domain awareness.(Maritime Domain Awareness in the Department of Defense)