Cruise around the San Francisco Bay

Was visiting San Francisco for a couple of days, and wandered near the San Francisco Bay. There are these ferries over there that take people around the bay in a 1 hour trip, including a circle around The Rock and under the Golden Gate Bridge. There is a running commentary through radios that are provided, and overall, it seemed a nice 1 hour spent.
It whetted my appetite for spending a longer time on the harbour the next time and maybe actually visit The Rock.