The Palo Alto Baylands Nature Preserve, known officially as the Baylands Nature Preserve, is the largest tract of undisturbed marshland remaining in the San Francisco Bay. Fifteen miles of multi-use trails provide access to a unique mixture of tidal and fresh water habitats. The preserve encompasses 1,940 acres in both Palo Alto and East Palo Alto, and is owned by the city of Palo Alto, California, United States.