Lead Researcher: Ralph Schneider, Christian-Albrechts-University, Kiel, GermanyThe research activities will take place exclusively offshore onboard the German research vessel (RV) Maria S. Merian from August 15th (departure: St.John’s, NF) to September 20th 2023 (end : Nuuk, Greenland).The cruise will focus on specific sectors or Hudson Strait, Foxe Basin and Hudson Bay during a period of 30 days. A total of 40 participants will be boarding the vessel (20 crew members and 20 scientists) from the entire duration of the expedition. The expedition will not take place in any protected areas, both marine and terrestrial. The expedition will aim at increasing our understanding of the Hudson Bay/Strait marine system in regards to (1) the impacts of the changing climate in marine and freshwater circulation, winter sea-ice conditions and CO2 gas exchange with the atmosphere and (2) its long-term evolution in respect of the history of glaciation, sea-level changes and past climate changes. Hydroacoustic surveys (multibeam and subbottom profiler sonars), sediment coring and water mass chemistry should provide a better spatial and temporal coverage to investigate the changes physical and chemical water column properties as well as in circulation at decadal to millenial time scales. Similar oceanographic expeditions collecting similar data have been undertaken during the last two decades by many survey vessels, including the CCGS Amundsen, without environmental impacts. The data collected during the cruise will allow increasing substantially the bathymetric mapping coverage of the region. These maps and datasets have great socio-economic benefits, especially for a safer navigation and for seafloor habitat management, and will be made available to the communities. The results of this expeditions will also allow evaluating the short and long terms impacts of climate change on the marine ecosystem of the Hudson Bay/Strait – Foxe Basin region.