Crissy Marsh is a wetland area in San Francisco, California, United States. Crissy Marsh has brackish waters, making an ideal habitat for many bird species along the Pacific Flyway. Here, freshwater runoff meets the salt water of the bay. It is 130-acres and located on the northern end of the San Francisco Peninsula. This salt marsh was largely destroyed to build Crissy Field, an airfield used during World War I and World War II. It has since been restored, with the airfield being removed. It now hosts abundant and recovering wildlife on the northern San Francisco coast.