Because of the overflow of river Wisla a great part of the expedition was destinated to the Southeast of the Baltic to study the effect of the overflow in the area of the Bay of Gdansk. To facilitate this the regular programme was reduced. Temperature, salinity and fluorescence (biological activity) at 4m depth were registered continuously throughout the expedition. Over great areas in the Southern Baltic and West Gotland a strong bloom of mainly bluegreen algae was observed. In the Bay of Gdansk the biological activity was even higher than in the surrounding sea. The biological activity around the Swedish south coast and in the Sound increased significantly during the duration of the cruise. In the Western Gotland Basin and in the Bornholm Basin bottom oxygen concentration was below 0.5 ml/l, a decrease since the latest measurements in June. Hydrogensulphide was found in the Eastern Gotland Basin at stations BY20 and BY15 from approximately 175m.