Deep water formed around the Antarctic continent drives the world ocean circulation. More than50% of this deep water is formed within only about 10% of the Antarctic circumpolar band: the Weddell Sea. Subtle changes in the circulation of the Weddell Sea can lead to major changes infloating ice-shelves, with critical implications for global sea-level, the production of deep water,the global ocean overturning circulation, and the associated carbon pumps of the Southern Ocean.The WAPITI cruise aims at zooming onto the source region of Antarctic Bottom Water, where potential changes at A23 would originate. In particular, Antarctic Bottom Water are formed by relatively warm current that enters in contact with ice-shelves. We will investigate the processes controlling the on-shore transport of relatively warm water onto the shelf toward the ice-shelves. Specifically we aim at observing the circulation (seasonality, timescale) and forcing (tide, sea-ice, air-sea) of the circulation on the continental shelf, and make unprecedented measurements of the biological and physical carbon pumps and associated acidification.