Iceland is a Nordic island country in the North Atlantic Ocean and the most sparsely populated country in Europe. Iceland's capital and largest city is Reykjavík, which is home to over 65% of the population. Iceland is the only part of the Mid-Atlantic Ridge that rises above sea level, and its central volcanic plateau is erupting almost constantly. The interior consists of a plateau characterised by sand and lava fields, mountains, and glaciers, and many glacial rivers flow to the sea through the lowlands. Iceland is warmed by the Gulf Stream and has a temperate climate, despite a high latitude just outside the Arctic Circle. Its high latitude and marine influence keep summers chilly, and most of its islands have a polar climate.