Hammarby sjö (Swedish: "Lake Hammarby") is a watercourse in central Stockholm, Sweden. Separating Stockholm City Centre from South Stockholm, or, more locally, Norra Hammarbyhamnen on eastern Södermalm from Södra Hammarbyhamnen, it connects Saltsjön to Årstasjön.Covering a surface of 34 hectares and having an average depth of 4.5 metres (maximum 6 metres), Hammarby sjö is supplied by a drainage area covering 159 hectares and contains 1,600,000 cubic metres of water.