Vistula Lagoon Vistula Lagoon The Vistula Lagoon (; or "Kaliningradskiy Zaliv"; ; ) is a brackish water lagoon on the Baltic Sea roughly 56 miles (90 km) long, 6 to 15 miles (10 to 19 km) wide, and up to 17 feet (5 m) deep, separated from Gdańsk Bay by the Vistula Spit. It is now known as the Vistula Bay or Vistula Gulf. The modern German name, "Frisches Haff", is derived from an earlier form, "Friesisches Haff". The lagoon is a mouth of a few branches of the Vistula River, notably the Nogat, and the Pregolya River. It is connected to
Keta Lagoon ponds. This is evidenced by the remains of oyster shells that are deposited at various spots in towns to the northern side of the lagoon. A third theory is that during the ice age these spots were the remains of the ice which melted due to rise in temperature leaving behind a fresh lagoon. The infiltration of sea water made it saline. The Köppen Climate Classification is "Aw". (Tropical Savanna Climate). Seva is an island located in the Keta Lagoon. By 2010, it has a population of 300 people with a terrain elevation of 43 metres above sea level. It