Baptism, as the bible teaches, is the full immersion of a believer into water. Once a person makes the decision to believe that Jesus is Lord & Savior just as He claimed to be and has done for us what He promised, the outward expression of that internal decision is to be baptised. Symbolically, as you enter down into the water you are identifying with the death of Jesus. Just as He died and was placed in a tomb, we recognise that our sinful lives have died and are now buried in the waters of baptism.
Jesus not only died and was buried, but also resurrected and returned back to life – likewise we also rise up out of the waters of baptism signifying that we are raised with Jesus & transformed into the new life He gives us. There is nothing magical or super spiritual about the water or the event itself, but rather is a public act of faith and confession that we do in fact believe in the saving power of Jesus that comes through faith in His death and resurrection.