Mar de Grau (Spanish: Grau's Sea) is the official name for the body of water in the Pacific Ocean under the control of the South American country of Peru. This body of water extends in length approximately 3079.50 km, from the parallel of the Boca de Capones in northern Peru to the parallel of the Punto Concordia and the parallel in front of the city of Tacna in southern Peru. In terms of width, the maritime zone extends from the Peruvian coast to 200 nautical miles (370.4 km) into the Pacific Ocean.
This maritime domain was officially named on May 24, 1984, in honor of Miguel Grau Seminario, a Peruvian military officer described in Peru and Bolivia as a hero from the War of the Pacific fought against Chile. During the war, Grau led the defense of the Peruvian and Bolivian coasts by holding off the Chilean navy for six consecutive months, ultimately dying at sea amidst the decisive Battle of Angamos.