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
Gdansk 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.