Bio-Bio Region

central Chile, bordering Argentina to the east and fronting the Pacific Ocean to the west. It was given its present boundaries in 1974. Its area of 14,262 square miles (36,939 square km) includes the provincias of Ñuble, Concepción, Arauco, and Bío-Bío. The islands of Santa María, in the Bay of Arauco, and Mocha, 14 miles (23 km) offshore, are part of Arauco provincia. Bío-Bío región spans the coastal mountain range, the cool, fertile Central Valley, and the Andean cordillera. Bío-Bío región is drained in the north by the northwestward-flowing Itata River and its main tributary, the Ñuble River, and in the south by one of Chile's major rivers, the Bío-Bío, and its principal tributary, the Laja River.