Synonyms of the word

unfathomed

• adj. Of unknown depth.
• adj. Not explored or understood.

deep

• adj. (heading, of a physical distance) Extending far away from a point of reference, especially downwards.
• adj. (heading, intellectual, social) Complex, involved.
• adj. (sound, voice) Low in pitch.
• adj. (of a color) Dark and highly saturated.
• adj. (sleep) Sound, heavy (describing a state of sleep from which one is not easily awoken).
• adj. Immersed, submerged (in).
• adj. Muddy; boggy; sandy; said of roads.
• adv. Deeply.
• n. (literary, with "the") The deep part of a lake, sea, etc.
• n. (rare) A deep shade of colour.
• n. (US, rare) The profound part of a problem.
• n. (with "the") The sea, the ocean.
• n. (cricket) A fielding position near the boundary.

profound

• adj. Descending far below the surface; opening or reaching to great depth; deep.
• adj. Very deep; very serious.
• adj. Intellectually deep; entering far into subjects; reaching to the bottom of a matter, or of a branch of…
• adj. Characterized by intensity; deeply felt; pervading.
• adj. Bending low, exhibiting or expressing deep humility; lowly; submissive.
• n. (obsolete) The deep; the sea; the ocean.
• n. (obsolete) An abyss.
• v. (obsolete) To cause to sink deeply; to cause to dive or penetrate far down.
• v. (obsolete) To dive deeply; to penetrate.

unplumbed

• adj. Not measured for depth, as if with a plumb.

unsounded

• adj. unfathomed.