The Curonian Lagoon is a nontidal lagoon on the southeastern edge of the Baltic Sea, with an average depth of just 12 ft (3.8 m). The Neman River flows into the lagoon’s northern (Lithuanian) section, which discharges into the Baltic via a narrow channel, the Klaipeda Strait. While most of the lagoon consists of fresh water, seawater sometimes enters its northern part via the Klaipeda Strait following storms. In the past, the lagoon has suffered heavy pollution from sewage and industrial effluents, but attempts are now being made to address this problem.
The lagoon is separated from the Baltic by the narrow, curved Curonian Spit, which is 60 miles (98 km) long. The spit is notable for its mature pinewoods and drifting barchans (sand dunes), some reaching a height of 200 ft (60 m), which extend for 20 miles (31 km) along the spit. The sandy beaches on the spit, together with vistas over the lagoon, woods, and drifting dunes, make it a tourist attraction, and in 2000 the entire spit was designated a UNESCO World Heritage site.