I would have expected you had gone beyond the Greek meaning of the word to try to defend submerging. However, you are mixing words: baptein means to dip, but baptizein has more meaning and you can see it in the Bible being used in the rite when the Jews pour water on the hands for washing (Luke XI, 38).

Notice that burial, and rebirth from water, is not a burial for the body, as is not the body that requires water, but the soul.

You do require water (the first and purest element), and water is then to be poured onto the head. Such as been bestowed of the Holy Ghost (read more about it below). Baptismal waters go into your soul (not into, around, etc. your body), and by been buried with Christ you can walk a new life.

We, little fish, according to our FISH Jesus Christ, are born in water, and we only live divine life while we remain in water (Tertullian). And we are after baptism being carried out in water, as the Holy Ghost (Genesis), who sanctifies water when invoked upon it, and thus leads us into sanctity.
But we are not living under water, it is just the baptismal ("Holy-Ghosted") waters that entered into our soul during the rite.