I: In the deep sea. The ocean is devided in several depth zones based on physical and biological properties of the waterlayers. Abyssopelagic is used for the deepsea (> 6000m) in the very deep trenches like the Marianen Trough. See also zonation

II: Abyssal is also a part of the common name of the Abyssal smooth head, Rinoctes nasutus, family Alepocephalidae and the Abyssal spiderfish, Bathypterois longipes, family Chlorophthalmidae.

Alternative forms for abyssal : abyssal zone, abyssopelagic.