Iceland is an island republic in the North Atlantic Ocean. Large snowfields, glaciers, volcanos, hot springs (which are used to heat homes in Reykjavik) and a deeply indented coastline are features of this rugged island. The warm North Atlantic Drift keeps the southern coats ice-free in the winter. Summers are cool. Less than 1 percent of the land is cultivated; the main crops are hay and potatoes. Iceland has also few tens of thousands of cattle and something over 800,000 sheep, but fishing is the main industry. Norwegian vikings colonized Iceland in 874. In 1262 it was united with Norway and, in 1380, it came under Denmark. Independence was achieved in 1918 although it stayed under the nominal rule of the Danish monarch. It became a republic in 1944. between 1958 and 1976 it was involved in various fishing disputes. In 1963 it acquired a new volcanic island, Surtsey, which appeared from the sea near Iceland.