The German research icebreaker RV Polarstern drifted within the western Weddell Sea pack from 27 November, 2004 until 2 January, 2005, initially anchored to a 10 km x 10 km sized floe. This was composed of 2-m thick second-year ice with 0.8 m snow on top, interspersed by first-year ice with modal thicknesses of 0.9 m and 1.8 m, covered with 0.3 m of snow. ISPOL traveled over a distance of 290 km with a net south-north displacement of 98 km due to various loops in the ice floe trajectory. These loops seem common since ISW-1 and tagged ice floes and icebergs followed similar deflections during their course. For 36 days Polarstern served an interdisciplinary scientific team from eight countries (Australia, Belgium, Finland, Netherlands, Russia, United Kingdom, U.S.A., and Germany) as accommodation and laboratory as well as platform for field and water column studies. The local view was extended to both sides of the floe trajectory using helicopters with an operational range of 120 km to conduct sea ice thickness and ice dynamics measurements, iceberg marking, and water column sampling. On 2 December, 2004 the floe cracked into several pieces, reducing the main station floe to a size of 1.5 km x 1.5 km. On 24 December the ice floe again fractured, leaving a piece of 0.7 km x 0.8 km for the remaining experiment.