Angel Island In 1775, the packet San Carlos, first known Spanish ship to enter San Francisco Bay, anchored in this cove while her commander, Lieut. Juan Manuel de Ayala, directed the first survey of the bay. Ayala named this island Isla de los Angeles. The island has been a Mexican rancho, a U.S. military post, bay defense site, and both a quarantine and immigration station. California Registered Historical Landmark No. 529