This fort, along with Fort Worden in Port Townsend and Fort Casey on Whidbey Island, was constructed as part of an "Iron Triangle" of defense for Puget Sound. Take in sweeping views of Whidbey Island's magnificent bluffs and Port Townsend's Victorian skyline from what is now a 784-acre historic state park tucked on the northern tip of Marrowstone Island. Built in 1897 and surrounded by saltwater on three sides, Fort Flagler was a military training center through the world wars, and still has old gun placements overlooking its rocky, log- and driftwood-strewn beaches. The park has 57 campsites with full hook-ups, 3.6 miles of coastline, and 5 miles of hiking and biking trails. Island inlets are great for paddling around; you can rent canoes and kayaks—and stock up on picnic items—at Nordland General Store (360/385–0777, nordlandgeneralstore.com), the island's only grocery store.