 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.Originally a lake about 3 metres deep, it was transformed into a canal when connected to Saltsjön in the 1920s and a 6 metres deep channel was dug between and Saltsjön and another to .The importance of the water expanse has grown since the late 20th century as new residential areas have been constructed along its shores.