submerge

(verb) sink below the surface; go under or as if under water. Synonyms: submerse.

(verb) cover completely or make imperceptible. Synonyms: drown, overwhelm. Examples: "I was drowned in work." "The noise drowned out her speech."

(verb) put under water. Synonyms: submerse. Example: "Submerge your head completely."

(verb) fill or cover completely, usually with water. Synonyms: inundate, deluge.