[1] The state park occupies 1,451 acres (587 ha) south of the entrance to Admiralty Inlet, and the Marrowstone Point Light stands adjacent.

Admiralty Inlet was considered so strategic to the defense of Puget Sound that the three forts were placed at the entrance with huge guns creating a "triangle of fire."

The post was named for Brigadier General Daniel Webster Flagler, an American Civil War veteran who served as the Army's Chief of Ordnance.

[1] Fort Flagler has hiking and biking trails, campsites, group campsites, boat launches, and historical buildings where visitors can stay - the Hospital Steward's House, the Waterway House, and the North and South Non-Commissioned Officers' Quarters.

[1] The park plays host to the annual conferences and meetings of many area cultural and athletic groups.