The Vistula Spit is an aeolian sand spit, or peninsular stretch of land, separating Vistula Lagoon from Gdańsk Bay, in the Baltic Sea, with its tip separated from the mainland by the Strait of Baltiysk. The border between Poland and Kaliningrad Oblast, an exclave of Russia, bisects it, politically dividing the spit into two pieces between the two countries. The westernmost geographical point of Russia is located on the Vistula Spit. The Polish part contains a number of tourist resorts, incorporated administratively as the town of Krynica Morska.

The Vistula Lagoon is a brackish water lagoon on the Baltic Sea roughly 56 miles (90 km) long, 6 to 15 miles wide, and up to 17 feet (5 m) deep, separated from the Gdańsk Bay by the Vistula Spit.