From the plaque:
In 1775, the packet San Carlos,
first known Spanish ship to enter San Francisco Bay, anchored
in this cove. While here, the commander, Lieut. Juan Manual
de Ayala, directed the first survey of the bay. This island,
which Ayala named Isla de los Angeles, has been a Mexican
rancho, a U.S. military post, a bay defense site, and
a quarantine and immigration station.
Plaque placed by the State Department of Parks and Recreation in cooperation with the City of Tiburon.
September 26, 1970