Wiktionary
n. A long, deep depression or trench in the ocean floor
WordNet
Usage examples of "oceanic abyss".
Dwer tried to cultivate patience, ignoring an itch where the bulky suit would not let him scratch, watching the lights disperse-most heading for the mouth of the Rift, spilling into the vast oceanic abyss of the Great Midden itself.
Rift, spilling into the vast oceanic abyss of the Great Midden itself.
The silence of the house, as deep as water in an oceanic abyss, was a crushing, immobilizing pressure.
Finding the professor again would mean relocating a specific fix and that would be like dropping a line into the oceanic abyss for the purpose of dredging up a particular fish.
Finding the professor again would mean relocating a specific fix across five million years or thereabouts and that would be like dropping a line into the oceanic abyss for the purpose of dredging up one particular fish.