Fort Flagler State Park is a Washington state park on the site of Fort Flagler, a former United States Army fort at the northern end of Marrowstone Island.
Fort Flagler was a Coast Artillery fort. It was established in 1897 and activated on in 1899. The post was named for Brigadier General Daniel Webster Flagler, an American Civil War veteran who served as the Army's Chief of Ordnance. The fort was closed in June 1953.
From Fort Flagler State Park, visitors can see Port Townsend to the northwest, the cranes at the Navy base on Indian Island to the west, and Whidbey Island eastward across Admiralty Inlet. Flagler Road (SR 116) terminates inside the park.