Gulf of California

Gulf of California, arm of the Pacific Ocean, separating the peninsula of Baja California from the mainland of Mexico. The gulf was known originally as the Sea of Cortés because the Spanish conqueror Hernán Cortés in 1539 sent an expedition to explore the area. The gulf is 1,100 km (700 mi) long and reaches a maximum width of 240 km (150 mi). At its upper end it receives the Colorado River, and from the east it receives several streams, chief of which are the Sonora, Yaqui, and Fuerte. Its shores are bordered by highlands, broken by the river valleys on the east but presenting an almost unbroken mountain wall on the west. The coastline is irregular and forms numerous small bays. The gulf contains many islands, particularly in the upper part, the largest of which are Ángel de la Guarda and Tiburón. On its western shore are the ports of San Felipe, San José del Cabo, and La Paz; on its eastern shore, the ports of Mazatlán and Guaymas. Pearl fisheries are on the western coast. The gulf is also a winter breeding area for the Pacific gray whale.