Water represented the will of the Father for the Son at His First Advent.
As Jesus came up out of the water, the Holy Spirit, the Third Person of
the Trinity, descended upon Him "in a bodily shape like a dove"
By this prearranged signal, John knew beyond a shadow of a doubt
that this One was indeed the Son of God, the Second Person of the
Trinity (John 1:33, 34).
And lo a voice from heaven, saying, This is My beloved Son, in
whom I am well pleased.