Alcatraz was a maximum security prison located in the middle of San Francisco Bay?. The ferry leaving from Fisherman's Wharf in San Francisco will take you right to Alcatraz. You can only get to Alcatraz by this scheduled ferry and must purchase in advance, as they sell out most of the time.
The island is now the site of the abandoned prison and the oldest operating lighthouse on the West Coast of the United States.
Make sure you wear something warm. The temperature drops about 10 degrees once you leave the mainland. Some people say it is haunted.