Lithuania, officially the Republic of Lithuania is a country in Europe, and is one of the three Baltic states. Situated along the southeastern shore of the Baltic Sea, it shares borders with Latvia to the north, Belarus to the southeast, Poland, and the Russian exclave of the Kaliningrad Oblast to the southwest. Its population is 3.4 million. Its capital and largest city is Vilnius. Lithuania is situated in Northern Europe. It has around 99 kilometres (61.5 mi) of sandy coastline, of which only about 38 kilometres (24 mi) face the open Baltic Sea and which is the shortest among the Baltic Sea countries; the rest of the coast is sheltered by the Curonian sand peninsula. Lithuania's major warm-water port, Klaipeda, lies at the narrow mouth of the Curonian Lagoon, a shallow lagoon extending south to Kaliningrad. The main river, the Neman River, and some of its tributaries carry international shipping vessels. The Lithuanian landscape has been smoothed by glaciers. The highest areas are the moraines in the western uplands and eastern highlands, none of which are higher than 300 metres (1,000 ft) above sea level, with the maximum elevation being Aukštojas Hill at 294 metres (964 ft). The terrain features numerous lakes, Lake Vištytis for example, and wetlands; a mixed forest zone covers nearly 33% of the country. The climate lies between maritime and continental, with wet, moderate winters and summers.