Among these, the Lofoten Islands are the largest and also a very popular tourist attraction. The climate is temperate, and the severity of winter along the coast is moderated by southerly air currents brought in above the waters of the North Atlantic Drift, which is warmed by the Gulf Stream. The rivers contain abundant salmon and trout, which are among the country's most famous exports. Spruce and pine are the most common trees in Norway's forests, and deciduous trees, such as birch and ash, are common in the lowlands. In the mountain regions, heather is abundant, as well as low bushes that provide numerous delicious berries.
Timber is one of the foremost natural resources.
In addition, Norway has tremendous resources in its offshore oil and gas fields in the North Sea as well as in the hydroelectric potential of the numerous rapids and waterfalls. Iron and copper are also mined. Norway emerged as an industrial nation from the beginning of this century, partly due to local elites investing money in shipbuilding, woolspinning, timber and pulp production, and partly because of foreign companies building up on electrochemical industry based upon cheap hydro-electric power. Norway has also had one of the biggest merchant fleets of the world. The financial surplus made by this type of service made it possible to outweigh the deficit of trade with other countries, and hence is an important economic and political factor in Norwegian history.