Meaning of baptism water

1 Peter 3: 17-22
Christ died for sins once for all, the righteous for the unrighteous, to bring you to God.
He was put to death in the body but made alive by the Spirit, through whom also he went and preached to the spirits in prison.
The water symbolizes baptism that now saves you also- not the removal of dirt from the body but the pledge保證 of a good conscience toward God.
Who are the spirit in prison? Are they unbelievers who have dies; Old Testament believers who have died; fallen angels?
What did Christ preach? Was it a second chance for repentance; the completion of his redemptive work; final condemnation?
When did he preach? Was it in the days of Noah; between his death and resurrection; after his resurrection?
Why?
Wane Grudem argues the view, from parallels in Jude ad 2 Peter, takes the 'spirit in prison' as fallen angels who are in tartaros(no hell) - a holding cell also referred to by Isaiah. The point of this proclamation is not redemption but to declare victory over the powers of darkness.
The flood-water which destroyed the world saved Noah and his family by floating the ark, so Peter sees the water of baptism as a symbol of rescue from death. It was the ark, not the water, which really saved Noah - as it is the risen Christ, not baptism in itself, who saves those who trust him and are cleanse from sin.
Baptism is a symbol for the pledge of good conscience toward God. The salvation is come from Christ Jesus.
How?
Made good behavior to witness of God, which bring them to God. Baptism water can not clean the dirt, cleanse from sin, but the pledge of good conscience toward God.