Literary or formal word for a very deep, dark place, often used metaphorically for something profound or unfathomable.
He stared into the dark valley floor as if peering into an abyss.
その哲学書は人間の心の深淵に迫る。
That philosophy book delves into the abyss of the human mind.
Standard kanji form; it is a common news word.
Compound of 深 (deep) and 淵 (abyss, deep pool). The kanji combination directly conveys the meaning of a deep, dark place.