The use of offshore wind energy is dependent on relatively low depths of the sea ground. Today some offshore wind farms are planned within areas with up to 40 m depth. So it seems to be reasonable to select areas where the depth lies within this order. On this map the depth up to 55 m are displayed for the Baltic Sea. The total area flatter than 50 m is 260000 km^2. At 4 MW/km^2 this would be sufficient for 1000 GW of erected wind turbines and thus allows a careful selection of the best sites where negative environmental and other unfavourable effects can be minimized and the sites with better wind conditions could be chosen.