An armed sea force is a group of individuals that are trained to defend a country's coastlines. The term 'armed sea force' can be replaced with several synonyms, such as naval force, naval fleet, maritime force/armada, sea corps, naval brigade, oceanic battalion, marine/maritime corps, and naval battalion. These synonyms are often used interchangeably and represent different branches; however, they all share the same responsibility of protecting their nation's maritime borders. The armed sea force is critical in defending a country's coastline against illegal activities, such as smuggling and piracy, as well as in times of war to provide support to ground troops.