One of the likely consequences of global climate change is an accelerated global sea-level rise. Combined with other effects, such as land subsidence, storm impacts and tsunamis, it could cause serious increases in coastal vulnerability, such as loss of the shore zone accompanied by a dramatic reduction of the width of the beaches. The deltaic areas and low-lying coastal plains along the Marmaris-Fethiye coast, SW. Turkey, are experiencing a number of similar short- and long-term coastal problems. In addition historical earthquakes and tsunamis hit those areas many times in the past. Trenching and coring surveys for historical tsunami deposits, their geological and biochemical properties provided some new clues for the coastal vulnerability of the studied coast to tsunamis, as well as for the environmental assessment of the past.