Necochea is a port and beach city in the southwest of Buenos Aires Province, Argentina. The city is located on the Atlantic coast, along the mouth of the Quequén Grande River, 528 km (328 mi) from Buenos Aires and 120 km (75 mi) southwest of Mar del Plata. The city proper has 65,459 inhabitants per the 2001 census[INDEC] and is the seat of government for Necochea Partido.