深海带（Abyssal zone）所在的区域为海洋的底部。那里有着数量庞大的底栖动物群。“Abyssal”一词由希腊字ἄβυσσος派生而来，含意是深不见底。深海带处于海洋4000米至6000米的位置（13,123至19685英尺），其总面积在5亿平方公里以上。这里的海水盐分含量为35‰，与普通海水无异。该区域一片黑暗，深不见底，从来没有阳光可以照射至这一区域。

只有这里的“常住居民”（例如：叉齿鱼、乌贼、腔肠动物）才可以抵御住这一水域高达76兆帕（11000磅）的水压。这里的许多生物都拥有重心低的下巴，这有利于在砂中筛选食物。这片水域还有一个特点：这里的终年寒冷，食物匮乏。深海带的气温一般为2°C至3°C（35°F至37°F） 。

The abyssal zone or abyssopelagic is a layer of the pelagic zone of the ocean. "Abyss" derives from the Greek word ἄβυσσος, meaning bottomless. At depths of 4,000 to 6,000 metres (13,123 to 19,685 feet), this zone remains in perpetual darkness and never receives daylight. These regions are also characterised by continuous cold and lack of nutrients.The abyssal zone has temperatures around 2 °C to 3 °C (35 °F to 37 °F) through the large majority of its mass. It is the deeper part of the midnight zone which starts in the bathypelagic waters above. Its permanent inhabitants (for example, Riftia pachyptila, (the Giant tube worm) found near hydrothermal vents in the pacific ocean and the giant squid are able to withstand the immense pressures of the ocean depths, up to 76 megapascals (11,000 psi).