Quote Originally Posted by Trek420 View Post
check out Angel Island. It's a biiiiiiig island in the middle of the bay with lots of hiking (and some bike) trails, beaches, incredible 360 degree view of the bay.
+1 Angel Island is a treat indeed and you can rent bikes there. Also, the Grove in the Marina (on Chestnut) is nice for a mid-morning/afternoon coffee and a cool place to check out the locals

Have fun !