One hour tours Sa 11AM. Reached by the half-mile "Trench Trail" from the visitor center. It was built from 1845 to 1870 to defend the northern side of the peninsula from land-based attack.
Sources and licences
Guide text adapted from the Wikivoyage article "Gulf Islands National Seashore" by its contributors, available under CC BY-SA 4.0. Read on Wikivoyage · Contributors · CC BY-SA 4.0
