submerse

from WordNet (r) 3.0 (2006)

submerse
    v 1: sink below the surface; go under or as if under water [syn:
         {submerge}, {submerse}]
    2: put under water; "submerge your head completely" [syn:
       {submerge}, {submerse}]

from The Collaborative International Dictionary of English v.0.48

Submerse \Sub*merse"\, a. (Bot.)
   Submersed.
   [1913 Webster]