The North Sea is a marginal sea of the Atlantic Ocean located between Great Britain, Denmark, Norway, Germany, the Netherlands, Belgium, and France. It is a relatively shallow sea, averaging only 95 meters in depth. Historically, it was the territory of the Vikings and later became a central hub for the Hanseatic League. In the 20th century, the North Sea became globally significant due to the discovery of vast oil and natural gas reserves beneath its floor, primarily in the British and Norwegian sectors. Today, it is also becoming a leader in the green energy transition, hosting some of the world's largest offshore wind farms. The sea is notorious for its difficult navigation due to frequent storms, shifting sandbanks, and heavy fog. It remains one of the world's most productive fishing grounds, particularly for Atlantic cod and herring.