The surface water temperatures were between 8 and 11°C in the whole area. Oxygen concentrations below 2 ml/l were found at depths greater than 70m in the Bornholm Basin and in the Landsort Deep, at 80m or deeper in the northern and eastern Gotland Basin. Hydrogen sulphide was present from 150 m in the Eastern Gotland Basin and from 80m in the Bornholm Basin. In the surface water the nitrate concentrations were between 0,2-0.3 μmol/l and the phosphate concentrations were of the level 0.1-0.2 μmol/l. The values of ammonia were higher in the southern Baltic - 0.9 μmol/l at station BY1- to be compared with a normal value of 0.1-0.2 μmol/l.