'Deepest' in the Bible

For the word of God is living and active and full of power [making it operative, energizing, and effective]. It is sharper than any two-edged sword, penetrating as far as the division of the soul and spirit [the completeness of a person], and of both joints and marrow [the deepest parts of our nature], exposing and judging the very thoughts and intentions of the heart.

For if God did not spare angels when they sinned, but threw them into the lowest hell and imprisoned them in chains of deepest darkness, holding them for judgment;

He has also held in eternal chains those angels who did not keep their own position but abandoned their assigned place. They are held in deepest darkness for judgment on the great day.

They are wild waves of the sea, churning up the foam of their own shame. They are wandering stars for whom the deepest darkness has been reserved forever.