Lake Peipsi is the fourth largest inland body of water in Europe. Its geological history was controlled by glacial retreat, climate and neotectonic movements. The lake depression has a key position between Russia, Estonia, Latvia and Finland for solving many principal problems related to the deglaciation history and neotectonical movements. The northern part of the meridionally elongated basin is now rising, the central part is stable and the southern part is sinking. These processes caused and are still causing the water to spread from north to south. The resultant flooding of large areas poses many ecological and social problems. Owing to considerable water-level fluctuations, exceeding 3m, both the surface area and the volume of the lake vary greatly. High-water levels cause remarkable damage on shores and pose a serious threat to the buildings and roads in the immediate vicinity of the lake. Extensive changes on the coast are also due to the action of hummocky lake ice. Lake Peipsi has a variety of shores. Shore types are determined by the coastal topography and lithology of the initial rocks. Shoreline changes and beach erosion have been caused by several geological and hydrometeorological factors (tectonic movements, hardness of rocks, wind regime, wave action, ice-push, water-level fluctuations) and human activity. Warmer winters and concurrent increased cyclonic activity have had noticeable impacts on the lake coasts during last decades.