Lake Le Bourget is a deep, peri-alpine glacial lake originating from the last glacial, the Wurm. The lake has amassed over 250 m of sediment since the Last Glacial Maximum. Two seismic sparker surveys on the lake revealed the glacial and post-glacial sedimentary infill, the depth and the morphology of the Wurm erosion surface and penetrated the Riss-Wurm interglacial deposits as deep as the underlying Riss erosion surface. The density of the seismic grid and the high resolution of the data, even at greater depths, allowed a detailed study of the sedimentary processes and of their evolution throughout the deglaciation. Five main seismic facies characterise the basin fill. They are interpreted as glacial deposits, glacio-lacustrine sediments, proglacial lacustrine fans, alluvial fan deltas and authigenic lacustrine drape. These occur as a suite of deposits associated with the major lake tributaries and are the result of major changes in sediment supply and style of discharge into the lake. The three-dimensional facies associations within the basin fill document the history of the basin and its catchment area since the onset of the deglaciation.