The Sea of Marmara (SoM) is affected by large earthquakes occurring on the North Anatolian Fault. Numerous submarine mass movements have occurred and the most recent turbidites in the basins of the SoM have been related to historical earthquakes. Within the SoM, the occurrence of submarine mass movements and their size appears modulated by eustatic changes that can be accompanied by transitions between a salty marine environment and a brackish lake environment. Detailed analysis, using a 3D high-resolution seismic dataset, of stratigraphy over the last 500 ka, within a ponded basin of the Western High, shows that intervals of draped sedimentary reflectors alternate with onlap sequences that followed episodes of rapid sea-level rise, with a periodicity of approximately 100,000 years (corresponding to glacial cycles). Mass Transport Deposits (MTDs) occur within the onlapping sequences. Detail analysis of the youngest large slide, which probably followed the lacustrine transition to during Marine Isotopic Stage 4 is presented; and the possible triggering processes are discussed. The potential triggers of MTDs during this transition, in the context of the SoM are: (i) gas hydrate dissociation by pressure drop; (ii) changes in sediments supply and transport dynamics; (iii) variations in pressure and/or ionic strength in pores. The latter case appears the most suitable hypothesis, as salt diffuses out of the pores of the marine clay-rich sediment dominated by smectite at the beginning of low stand/lacustrine stages. The pore water freshening induces clay swelling, which can potentially drive sediment slope failure.