A marginal sea located in the North Atlantic Ocean. It is roughly defined as the waters lying to the west of Jan Mayen Ridge at about 7° W. It adjoins the waters of the Norwegian Sea to the east, the Greenland Sea to the north, the Denmark Strait to the west, and the North Atlantic Ocean to the south. The average depth of this region is about 1128 m. In the summer, the volume of the Iceland Sea is composed of about 60% Greenland Sea Deep Water (GSDW), 30% upper and lower Arctic Intermediate Water (AIW), with the remaining 10% distributed among the Polar Intermediate Water (PIW), surface water masses (i.e. Polar Water (PW), Atlantic Water (AW), and Arctic Surface Water (ASW)).