This was the last exposure of a very long day (see Hiding, Pacific Golden-Plovers, Alone in the City, and Bridge Time). I pointed the camera straight down on the cove directly to the northwest of the Golden Gate Bridge. I opened the shutter for three minutes, with the lens wide open.
Neat the way the light in the photo comes from the Golden Gate Bridge, but the bridge is never actually seen (you see the bridge shadow, of course).