The surface water temperatures were normal for the whole area. The nutrient concentrations were low in all sea areas, which is normal for the season due to the ongoing algal blooms. Oxygen concentrations below 2 ml/l were found on depths under 80 m in the Western and Eastern Gotland Basin, and under 70 m in the Bornholm Basin. Hydrogen sulphide was present near the bottom in the Eastern Gotland Basin and in the Bornholm Basin. Optical measurements on total and suspended organic matter were also carried out within the RESE project.