The general objective of the project that this cruise is part of is to study the Quaternary evolution of the Seine bay. It involves understanding how the different morpho-sedimentary units were put in place during the end of the Quaternary and how they have evolved since the beginning of the Holocene high sea-level stand. The final objective is to build a model for this type of sedimentary basin represented by a vast megatidal bay that has specific architecture in a well defined stratigraphic framework, to specify the geometrical relations between the coastal entities and define the role of the morphology and the nature of the underlying geological substrate, including the network of paleovalleys, in the location, shape and evolution of these various entities. These studies were undertaken in the frame of a thesis by F. BenabdelHouahed, co-financed by the Lower Normandy regional council and BRGM. Following the BaieSeine cruise surveying the entire area in 2007 and the Seine VHR in the coastal domain in June 2008, the SeineHR cruise enabled the 1st phase of studies to be completed and a grid of seismic data covering the entire study area to be established. The cruise was related to the BRGM Land-Sea Transition research project.