Visit to the Alcatraz Island.
"Why would I wanna go visit a prison?" that's the first thing I said when I was looking for recommendation of places to visit while in SF. Haha but after some research this become my first place to visit when I arrive. It's got some funny history to it.
Not quite a functional fort. Cool prison idea but not very evergreen. This place got famous especially in the movie "Escape from Alcatraz". Now it serves as a very profitable travel site.
I saw a shark on the way back with ferry. I think that great white shark attack clip on Youtube spotted at the island is quite legit.