to immerse someone or something in a liquid. The preacher submerged Jeff in the water of the river as part of the baptism ceremony. Submerge the fish in the marinade for at least two hours.
to put someone or something below the surface of a liquid. The maid submerged her mistress under the surface of the water for a moment and brought her up and dried her off. They submerged themselves under the surface of the water and had a look around.