The Sea Lion Center, a free attraction in San Francisco, offers the fascinating history of the sea lions of Pier 39. These photogenic creatures have been barking it up at Pier 39 since 1989. Since that time, tourists were mainly left to wonder about the habits, diet, and lifespan of these amazing sea animals. The Sea Lion Center, with its cheery and informed volunteer staff, takes the experience to a whole other level with interactive exhibits and informative videos. Although the Sea Lion Center is free, they definitely accept donations to keep their helpful and fascinating programs running. And you can't beat the view of the Bay from right outside their doors.