The deep part of the ocean, now typically from a depth of 3000 metres (1.9 miles) down to 6000 metres (3.7 miles), though the numerical limits, especially the upper one, vary.
Origin
Mid 19th century.
Definition of abyssal zone in US English:
abyssal zone
noun
The deep part of the ocean, now typically from a depth of 3000 metres (1.9 miles) down to 6000 metres (3.7 miles), though the numerical limits, especially the upper one, vary.