A temperature survey in the upper 200 feet of coastal waters of Baja California, from Bahia de Todos Santos to Bahia de la Magdalena, during the spring of 1950, has demonstrated the occurrence of upwelling along virtually the entire coast except within Bahia Viscaino and between Lat. 24° 50' and 26° N. A study of the marine vegetation of this coast and of the outlying islands has shown close correlation with the presence or absence of upwelling water....