The temperature and nutrient concentrations in the surface layer were normal for the season in most areas. The surface salinity on the West-Coast was 10 to 15 psu lower than normal. High nitrate concentrations were measured in the Arkona Basin, two times normal winter values. The spring bloom of phytoplankton was at its end on the West Coast while it was still ongoing in the Baltic Proper. Oxygen concentrations below 2 ml/l was found at depths greater than 70 to 80 metres in the whole Baltic Proper. Hydrogen sulphide was present at depths greater than 125 metres in the eastern Gotland Basin from 100 metres at the Karlsö Deep and from 175 metres at the Norrköping Deep.