Oslo is an important centre of maritime knowledge in Europe and is home to approximately 980 companies and 8,500 employees within the maritime sector, among which are some of the world's largest shipping companies, shipbrokers, and insurance brokers. The metropolitan area of Oslo has a population of 1,283,533 (2004), making it the fastest-growing Scandinavian capital.
Oslo occupies an arc of land at the northernmost end of the Oslofjord. The fjord, which is nearly bisected by the Nesodden peninsula opposite Oslo, lies to the south; in all other directions Oslo is surrounded by green hills and mountains. There are 40 islands within the city limits, the largest being Malmøya (0.56 km2/0.22 sq mi), and scores more around the Oslofjord. Oslo has 343 lakes, the largest being Maridalsvannet.
Oslo has a humid continental climate (Dfb according to the Köppen climate classification system). Because of the city's northern latitude, daylight varies greatly from more than 18 hours in midsummer to around 6 hours in midwinter. Despite its northernly location, the climate is relatively mild throughout the year because of the Gulf Stream.