Angel Island is an island in San Francisco Bay. The entire island is included within Angel Island State Park, administered by California State Parks. The island, a California Historical Landmark, has been used by humans for a variety of purposes, including seasonal hunting and gathering by indigenous peoples, water and timber supply for Europe…Angel Island is an island in San Francisco Bay. The entire island is included within Angel Island State Park, administered by California State Parks. The island, a California Historical Landmark, has been used by humans for a variety of purposes, including seasonal hunting and gathering by indigenous peoples, water and timber supply for European ships, ranching by Mexicans, United States military installations, a United States Public Health Service Quarantine Station, and a U.S. Bureau of Immigration inspection and detention facility.