Juan Rodriguez Cabrillo (also known under his Portuguese name Joćo Rodrigues Cabrilho) was born in Portugal, but lived most of his life in the Spanish New World colonies. He had already joined a few voyages of discovery (he had come to Mexico with Narvaez, shifted alliance to Cortes, helped the founding of the city of Oaxaca, and joined Alvarado in his mesoamerican conquests), and had become wealthy through goldmining in Guatemala, when in 1542 Antonio de Mendoza, the viceroy of New Spain (Mexico), asked him to explore the northern limits of New Spain's westcoast.
Cabrillo departed from Navidad (now called Acapulco) on June 27, 1542, and sailed north to Baja California. He went further along the coast, and discovered and named San Diego Bay and Santa Barbara. Although he reached Russian River, he missed Monterey Bay and San Francisco Bay (future discoverers would miss the Golden Gate as well, it was first found on the Portola expedition of 1769, which followed the coastline by land).
He turned back to find a place to spend the winter, and did so on San Miguel Island in the Santa Barbara Channel. Here he got into a fight with indians, and died of the complications of a broken leg. Bartolome Ferrelo took over charge of the expedition, and decided to make a new attempt to go further north. He rounded Cape Mendocino, and headed further north, reaching Rogue River (Oregon). After some more bad weather he made it safely back to Navidad.
In his days the Cabrillo expedition had no major impact. Spain did not make anything of its claims to California until the late 18th century, when colonization was started. Nowadays he is remembered as the discoverer and first explorer of the Californian coast.
Daniel B. Baker (editor): Explorers and Discoverers of the World. Gale
Research Inc., Detroit, 1993.
Richard E. Bohlander (editor): World Explorers and Discoverers. Macmillan, New York et al., 1992.