The Vistula Lagoon is a vast body of internal sea water, separated from the Gulf of Gdansk by the dunes of the Vistula Spit. Its area is impressive, as the Lagoon covers 382 square kilometres within Polish borders. This is as much as two and a half times Lake Śniardwy. The large surface area of the reservoir and the possibility of tacking, the wind often blowing in from the sea and the sea marking the fairways make sailing conditions comparable to those at sea.