I Peter 3:18-21

So Noah and his family were saved through water, an image that clearly points us to baptism, and baptism too is part of God's magnificent work of deliverance. Just as the waters of the Flood marked the passage from judgment to salvation for Noah, so the waters of baptism signify our passage from the old life into the new. In this way, the water of the Flood corresponds in profound and purposeful ways to the water we pass through in baptism, both standing as witness to God's saving power and gracious intervention.

Now Peter does not say that it corresponded in all aspects, for example, in respect to quantity or to the manner of the application or to the effectiveness, but there is a sense in which water plays an important part in our salvation. For baptism to be valid, it must be accompanied by genuine repentance and faith in Christ. It involves turning away from sin and living under the influence of God's Spirit. It is an act of unreserved dedication to God.

I Peter 3:20-21

One obvious example is Noah and the flood. Noah lived at a time when the earth was corrupt and filled with violence. Noah was a righteous man. By faith he prepared the ark in anticipation of the Flood. When the rain began to pour and waterspouts discharged tremendous amounts of water, Noah and his family were safely in the ark. Water cascaded over, under and around the ark. The New Testament tells us that this was definitely a type of baptism.