Home Postcode finder SA O'Sullivan Beach O'Sullivan Beach postcode SA O'Sullivan Beach is a locality in South Australia covered by postcode 5166. Postcode 5166 State or territory South Australia (SA) Region Adelaide Add a free O'Sullivan Beach business listing More business listings in O'Sullivan Beach Businesses in O'Sullivan BeachO'Sullivan Beach Primary School51 Galloway Beach Rd · 08 83825888Southern Montessori School53 Galloway Rd · 08 83847233 Common questionsWhat is the postcode for O'Sullivan Beach?O'Sullivan Beach, SA has the postcode 5166.What state is O'Sullivan Beach in?O'Sullivan Beach is in South Australia (SA).Does postcode 5166 cover more than one suburb?No. Postcode 5166 covers O'Sullivan Beach only, which is unusual - most Australian postcodes cover several localities. Browse other postcodes in South Australia, or widen the search to every Australian postcode.