1 Peter 3:21 (NKJV)

21 There is also an antitype which now saves us—baptism (not the removal of the filth of the flesh, but the answer of a good conscience toward God), through the resurrection of Jesus Christ,

The following is from:
Letters From Peter, Bruce Oberst, College Press, Joplin, Missouri
http://www.collegepress.com/cp/pdf/21%201%20and%202%20Peter.pdf

Expanded Translation
Which (that is, water) also now saves you in the antitype-baptism, which does not have to do with the removal of dirt from the flesh (i.e., the body, the outside of one), but to provide ground or reason for having a good conscience toward God (which comes when the one is right on the inside). All this is possible because of the resurrection of Jesus Christ;

which also after a true likeness doth now save you
LIKENESS – antitupos, meant first of all a thing formed after some pattern (Heb, 9:24), then a thing resembling another, its counterpart; hence, something in the Messianic times which answers to the type prefiguring it in the Old Testament. It is this very word from which we have the English word, “antitype.”
We understand that God was responsible €or their salvation, and it was through His mercy and love that He provided a means whereby they could escape the doom of the world, But the means He chose was water. Had Noah refused to accept the means God had provided, we could only call him rebellious, and he would have been lost.
Today, God has also provided a means whereby we may avail ourselves of His salvation, and where we may meet the blood of Christ. He has provided it in His mercy, kindness and love, but we must accept what He has provided. The Holy Spirit says baptism “doth now save you.” God saves us through the blood of Christ, BUT THE MEANS HE HAS CHOSEN IS WATER!

not the putting away of the filth of the flesh
BILTH-h~upos, filth, squalor, dirt. The purpose of baptism is not to obtain an outward cleansing. We can take care of that matter in the bathtub.

but the interrogation of a good conscience toward God
INTERROGATION-eperofema, W. E. Vine states that the word is not here to be rendered “answer.” It was used by the Greeks in a legal sense, as a demand or appeal. The word is often rendered “seeking.” The meaning is easily seen when this phrase is compared with the previous. The purpose of baptism is not to cleanse the outside. Rather, it is to gain a clean inside, that is, to gain or obtain a clear conscience toward God. Any true Christian can testify to the truthfulness of this verse in his own experience. When he met the blood of Christ in the baptismal waters by faith, and arose to walk in newness of life, his conscience no longer condemned him and the purpose for which he was immersed – to meet the blood of Christ-was fulfilled. He was “seeking” and he found! “Blessed is the man whose transgression is forgiven, whose sin is covered’’ (Psalm 32-1). If you have not obtained a clear conscience in baptism, then it has not fulfilled its purpose in your life!

through the resurrection of Jesus Christ
That is, all this is possible through the resurrection of Christ. If He had not arisen, our baptism would have been in vain and Christ would have no power to save us. See I Corinthians 15:12-14. His resurrection showed His power over death. For the exact relationship between His resurrection and our baptism, see Romans 6:l-6.

How was Noah’s family saved “through water”?
Of what is this a “true likeness”?
How can water save us? Is not the principle of the Jews true, “who can forgive sins, but God alone”? (Luke 5:21.)
What is baptism not for, according to Peter?
What does it obtain for one?
Explain the phrase “interrogation of a good conscience toward God,” v. 21,
Baptism is effectual because of what great event in the life of Jesus?