Home Postcode finder WA Koolan Island Koolan Island postcode WA Koolan Island is a locality in Western Australia covered by postcode 6733. Postcode 6733 State or territory Western Australia (WA) Region North West Suburbs Add a free Koolan Island business listing Be the first listing in Koolan Island Common questionsWhat is the postcode for Koolan Island?Koolan Island, WA has the postcode 6733.What state is Koolan Island in?Koolan Island is in Western Australia (WA).Does postcode 6733 cover more than one suburb?No. Postcode 6733 covers Koolan Island only, which is unusual - most Australian postcodes cover several localities. Browse other postcodes in Western Australia, or widen the search to every Australian postcode.