I went to the 14th annual SF Bay Flyway Festival on Sun 2/7/10. It's a 3-day event, but only went one day.
The Flyway Festival is a large birding event where you can look for birds, learn about Mare Island, go on boat tours that cost a lot of money, or do some FREE walks/hikes.
We did some hikes:
9:30-12 Mare Island historic south shore hike w/ Sierra Club hike leader With Kenn Browne. Walk along the Historic Southshore of Mare Island out to Pier 35 for great views of the San Pablo Bay and Carquinez Strait. We'll see the original Mare Island where 150 years ago the U.S. Navy sited its first West Coast ammunition depot and shipyard. We'll pass under heron and osprey nests, not active until spring and summer, but expect resting and feeding waterbirds in the protected waters off the Mare Island Southshore Heritage Preserve. This is a level 4-mile roundtrip walk on paved and gravel roads in an area not yet open to public access.
We walked to the Cemetery on our own & to the cool artwork "The Spirit Ship".
Then from 1-3:30pm went on the Sears Point Cougar Mountain Hike - about 20 min drive from Mare Island. Hike up Cougar Mountain with Justin Whitfield, URS Corp. Biologist, to learn about grassland ecology, the Sears Point Restoration, explore vernal pools, and take in the wonderful views of San Pablo Bay to San Francisco, Mt. Diablo, and Mt. Tam on a clear day. Meet at the San Pablo Bay National Wildlife Refuge Headquarters. Cool on the top for nice views & lots of sheep w/ pond on the top of the mtn.
Google: SF Bay Flyway Festival - usually around Feb 7-9 or whatever read more