深海

(1)literary term for an ocean; "denizens of the deep"

(2)海洋の文学用語

(3)a bottomless gulf or pit; any unfathomable (or apparently unfathomable) cavity or chasm or void extending below (often used figuratively)

(4)底無しの湾か穴

(5)底知れぬ（または、一見底知れぬ）穴、裂け目、または、空洞で、下に広がる（時に比ゆ的に）もの