The TRANSDRIFT III expedition was part of the joint Russian-German cooperation and the Laptev Sea System project. The Arctic and Antarctic Research Institute (AARI) in St. Petersburg and the GEOMAR Research Center for Marine Geosciences were jointly responsible for the organization and coordination of the TRANSDRIFT III expedition, which was funded by the Russian Ministry for Research and Technology and the German Ministry for Research and Technology.The TRANSDRIFT III expedition was carried out aboard the Russian icebreaker KAPITAN DRANITSYN in the Laptev Sea from October 1 to 30, 1995. In this shelf region a multi-disciplinary working program investigated the causes and effects of annual freeze-up. Unlike our previous expeditions to the Laptev Sea, which focused on oceanographical, hydrochemical, ecological and sedimentological processes during the brief ice-fee period in summer, this expedition studied these processes during the extreme physical change through the onset of ice formation in autumn. This was the first study of its kind under these conditions, and gave important clues to the rapid (14 to 40 days) freeze-up, which has significant year-round effects on the Laptev Sea and global environment.The working program was carried out in bilateral cooperation. CTD data were retrieved at a total number of 75 positions in the Laptev Sea. Hydrochemical sampling with oxygen, silicate and phosphate analysis was carried out at 65 of these stations.