Poland shares borders to the east with the Russian Federation, Belarus, Ukraine and Lithuania, to the south with the Czech Republic and the Slovak Republic and to the west with Germany. To the north lies the Baltic Sea. The Baltic coast provides over 500km (300 miles) of sandy beaches, bays, steep cliffs and dunes. Northern Poland is dominated by lakes, islands and wooded hills joined by many rivers and canals. The Mazurian Lake District to the northeast is particularly beautiful. Lake Hancza, the deepest lake in Poland, is located in this district. The River Vistula has cut a wide valley from Gdansk on the Baltic coast to Warsaw in the heart of the country. The rest of the country rises slowly to the Sudety Mountains, which run along the border with the Czech Republic, and the Tatra mountains, which separate Poland from the Slovak Republic. To the west, the River Oder, with Szczecin at its mouth, forms the northwest border with Germany.