Fort Casey Historical State Park is a 998-acre marine camping park with 10,810 feet of saltwater shoreline on Puget Sound (Admiralty Inlet); it includes Keystone Spit, a 2-mile stretch of land separating Admiralty Inlet and Crocket Lake. Fort Casey, Fort Worden and Fort Flagler together were known as the “Triangle of Fire,” a trio of strategically placed fortifications defending the entrance to the Puget Sound at the turn of the 20th Century.