Undercurrent

(n.) A current below the surface of water, sometimes flowing in a contrary direction to that on the surface.

Undercurrent - Other Definitions

(n.) A current below the surface of water, sometimes flowing in a contrary direction to that on the surface.
(n.) Hence, figuratively, a tendency of feeling, opinion, or the like, in a direction contrary to what is publicly shown; an unseen influence or tendency; as, a strong undercurrent of sentiment in favor of a prisoner.
(a.) Running beneath the surface; hidden.