The **Mexican Navy** (Secretaría de Marina, SEMAR) is Mexico's naval branch responsible for naval operations, maritime security, and coastal defense. Established in 1821, it is one of the oldest institutions in the country and is the second largest navy in Latin America and North America, after the United States[2][5][7]. The President of Mexico is the navy's commander-in-chief, with day-to-day operations overseen by the Navy Secretary who reports directly to the President[2]. The Navy’s organizational structure includes a General Headquarters based in Mexico City and three main naval forces: the Gulf and Caribbean Sea Naval Force, the Pacific Naval Force, and the Naval Infantry Force. The navy operates through eight naval regions, thirteen zones, and fourteen sectors along Mexico’s extensive coastlines[2][4]. Its fleet includes frigates, patrol vessels, and auxiliary ships, with key naval infrastructure including shipbuilding dockyards[1][4]. The **Naval Infantry Corps** (Marines) is a significant component, tasked with port security, coastal defense, and patrolling inland waterways. It comprises 30 battalions, including special forces and rapid reaction units, and is responsible for enforcing national service obligations among youth[2][3]. The Naval Infantry’s motto is *“En la Tierra, en el aire y en el mar”* (On land, air, and sea)[3]. The Mexican Navy plays a critical role in combating organized crime, drug trafficking, and maritime security threats, reflecting its modern focus on internal and external security challenges. Recent organizational reforms aimed to improve operational efficiency in these areas[1]. The Navy also maintains naval aviation and a training academy, the Heroica Escuela Naval Militar, which develops officers for its varied missions[2][6]. One of its training vessels, the A.R.M. Cuauhtémoc, built in 1981, is notable for naval cadet training[9]. In summary, the Mexican Navy is a vital institution for national defense and maritime security, with a strong historical legacy and ongoing operational relevance in Mexico’s security landscape.