The Gulf of Maine is a vast, highly productive cold-water sea area defined by its unique oceanography and rich biodiversity. This semi-enclosed body of water, bounded by the coastlines of Massachusetts, New Hampshire, Maine, and the Canadian Maritimes, features a complex bathymetry of deep basins, shallow banks, and channels. A counter-clockwise gyre, driven by the meeting of the Labrador Current and Gulf Stream and amplified by powerful Bay of Fundy tides, circulates nutrients throughout the ecosystem. The Gulf is notably deep, with an average depth of 490 feet and a maximum depth of 1,236 feet. A distinct thermocline typically occurs between 300 and 1,000 feet below the surface. Surface water temperatures are cold, ranging from about 50°F in winter to 63°F in summer. This nutrient-rich, cold-water environment supports a tremendous biomass of plankton, which forms the foundation for a diverse food web and a world-class fishery.