Skagit Island Marine State Park is a small public recreation area in Skagit Bay in northwestern Washington, centered on the 25-acre Skagit Island. About 1 mile east of Hoypus Point and 1.5 miles east of Cornet Bay in Deception Pass State Park, it is accessible only by boat. The island is wooded and includes occasional meadows, rock outcrops, beach, and a land trail. Its significance as a marine state park lies not only in its modest land area but also in its water setting, which defines the character of the park.