The joint South African - French partial submission for an area relating to the Prince Edward Islands and the Crozet Archipelago was lodged with the UN Commission on the Limits of the Continental Shelf on 6th May 2009. The MD176 Discovery Ridge - Crozetplac survey was designed to acquire bathymetric and geophysical data to provide substantiation of the natural prolongation of the Discovery Ridge as a submarine elevation and of the location of the 2500m isobath to allow the construction of the related +100M constraint line. An additional objective was to acquire multibeam echosounder profiles in the quadrant to the north-east of the Crozet Islands, to provide better substantiation of the location of the Base of Slope and of the Foot of Slope points that have already been included in the initial joint submission. The survey was conducted by the RV Marion Dufresne under contract from the French Polar Research Institute Paul Emile Victor (IPEV). The scientific team comprised experts from IPEV, the French oceanographic research institute, Ifremer, the French naval hydrographic office, SHOM and the South African Petroleum Agency. The primary data set acquired was multibeam echosounder, with gravity, magnetometer and 3.5kHz sub-bottom profiler constituting ancillary data sets. In order to optimise the acquisition of multibeam echosounder data, the sub-bottom profiler was only turned on at intervals to illustrate the nature of the sediments beneath the sea floor.