The Barents Sea (Norwegian: Barentshavet, Russian: Баренцево море) is a part of the Arctic Ocean locate north of Norway and Russia. It is a rather deep shelf sea (average depth 230 m), bordered by the shelf edge towards the Norwegian Sea in the west, the island of Svalbard (Norway) in the northwest, and the islands of Franz Josef Land and Novaya Zemlya (Russia) in the northeast and east. Novaya Zemlya separates Kara Sea from Barents Sea. Known in the Middle Ages as the Murman Sea, the sea takes its current name from the Dutch navigator Willem Barentsz. The southern half of the Barents Sea, including the ports of Murmansk (Russia) and Vardø (Norway) remain ice-free year round due to the warm North Atlantic drift. In September, the entire Barents Sea is more or less completely ice-free. Until the Winter War, Finland's territory also reached to the Barents Sea, with the harbor at Petsamo being Finland's only ice-free winter harbor.