Nice view, easy hike, muddy at places. Lots of birds. Multiple options, can walk as short as 2 miles, or a long loop of 9 miles.
I went there twice. First about 4 miles in and out from Alviso Marine County Park, along Alviso Slough. 2nd day, I went to the Environmental Education Center and walked back to Alviso Marine County Park, going through New Chicago Marsh, and Mallard Slough, maybe about 6 miles.
This is in the south San Francisco Bay.