There are ton of non-indigenous eucalyptus trees planted by the explosive companies, some of them are pretty big. To the right of the ruined foundation is one of the more minor paths, which look great for mountain biking, overall its probably a little bit limited spacewise for really tearing it up for more than an hour.
There is a freshwater pond with a couple large fields nearby.
And of course, as with any San Francisco bay area coastal park, you get great views.
Bay Area Hiker has a hike guide and more photos.