the.com/submergence

means The act or state of being plunged completely beneath a surface, usually water — or figuratively, being totally absorbed into a situation.

from Built from Latin submergere — sub ('under') plus mergere ('to dip, plunge'), the same root that gives English 'merge' and 'emerge.' The '-ence' ending turns the verb into a noun of state, so submergence names the condition of being fully dipped under, rather than the act of dipping itself.