Series of surface temperature observations and bathythermograms made during the late summer of 1948 and the spring of 1949 along the Central Pacific Coast of Baja California have revealed the presence of an area of inshore upwelling centering in the vicinity of Isla San Roque and Isla Ascunci6n. Supporting evidence is furnished by the fact that all but five of the 30 known species in the intertidal vegetation of these islands are characteristic of cool water localities to the north in California.