sentences:  Formerly home to the maximum-security prison, the island is located in San Francisco Bay; visitors take a ferry from Pier 33 in San Francisco to reach it.Once there, the Parks Conservancy now offers popular tours, attractions, and merchandise for visitors.Additionally, in partnership the National Park Service, the Parks Conservancy coordinates volunteer programs to ensure the island's restored gardens and wildlife habitats, home to some 20,000 sea birds, are carefully protected.