The Polish Baltic coast is approximately  long and extends from Świnoujście on the islands of Usedom and Wolin in the west to Krynica Morska on the Vistula Spit in the east. For the most part, Poland has a smooth coastline, which has been shaped by the continual movement of sand by currents and winds. This continual erosion and deposition has formed cliffs, dunes, and spits, many of which have migrated landwards to close off former lagoons, such as Łebsko Lake in the Słowiński National Park.