Fishing from the bay
Right next to today's Dumbarton Bridge, there's the original bridge from the 1920s, or at least, what's left of it. The middle part has been removed, and the two now-disconnected parts stick out into the bay from either end as fishing piers. If you're willing to navigate some back roads to reach a parking lot and then walk the rest of the way, you can get quite a way into the bay without getting wet.
I went for a walk out that way from the Fremont/Newark side last year and noticed something amusing along the way. Someone had mounted the base of a small satellite dish on the bridge rail!
I'm pretty sure nobody was actually trying to watch TV out there. There's a far easier explanation for this sort of thing. That base has a pipe which can be rotated around to a convenient angle and locked down. It looks solid, but it isn't. It's actually hollow.
In theory, you could get it swung around to an angle which works for you, and then put a fishing rod in there. It would stay there as long as you needed without having to stand there holding it forever. This particular spot isn't that deep (and really, this far south, nothing is), but at high tide I guess there might be some fish down there...
... and the occasional shark, believe it or not. This kid was proud of his catch and hauled it up to let me take a picture.
I really like the fact that even though the valley is full of technology, it's still surrounded by nature. You don't have to go far to find interesting habitats where the local inhabitants don't care about gigahertz, gigabytes or venture capital. They're only in it for the fish.
July 9, 2013: This post has an update.