GIUK gap

The GIUK gap is an area in the northern Atlantic Ocean that forms a naval choke point. Its name is an acronym for Greenland, Iceland, and the United Kingdom, the gap being the open ocean between these three landmasses. The term is typically used in relation to military topics.

The GIUK gap was particularly important to the British Royal Navy, as any attempt by northern European forces to break into the open Atlantic would have to be made either through the heavily defended English Channel, one of the world's busiest seaways, or through one of the exits on either side of Iceland. As the British also control the strategic port of Gibraltar at the entrance to the Mediterranean, this means Spain, France, and Portugal are the only Continental European countries that possess direct access to the Atlantic Ocean that cannot easily be blocked at a choke point by the Royal Navy.

Since the beginning of the twentieth century, the exploitation of the GIUK gap by northern forces and measures to patrol and secure the gap by opposing forces have played an important role in naval and in overall military planning.

From the start of World War II in 1939, German ships used the gap to break out from their bases in northern Germany (and from occupied Norway after April 1940) with a view to attacking Allied shipping convoys, but Allied blocking efforts in the North Sea and in the GIUK gap impeded such break-outs. British forces occupied the Faroe Islands in April 1940, and Iceland in May 1940; the United States of America took over effective control of Greenland in 1940. But the German Kriegsmarine profited greatly from the fall of France in June 1940, after which German submarines could operate from bases on the French coast. Between 1940 and 1942 the Denmark Strait between Iceland and Greenland remained one of the few areas that RAF patrol bombers could not reach, and thus became the centre for considerable action.

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