Fort Flagler is a historic military installation located on Marrowstone Island in Washington State. Established in the late 19th century, it was part of the coastal defense system designed to protect the Puget Sound from potential naval attacks. The fort features several well-preserved buildings, including barracks and gun emplacements, which showcase military architecture from that era. Today, Fort Flagler is a state park, offering recreational opportunities such as hiking, camping, and beach access. Visitors can explore the fort's historical significance while enjoying scenic views of the surrounding Strait of Juan de Fuca and Olympic Mountains.