Who has gone into heaven and is at the right hand of God, angels and authorities and powers having been made subject to Him.
Listen to the "Verse by Verse" episode covering this scripture.
The Word of God, who was with God the Father for eternity, came to earth as Jesus Christ to live a perfect, exemplary life and then die for our sins. After His death, He was resurrected to immortal life again and returned to heaven to the close relationship He has always had with the Father. Again the angelic host is under His authority.
The apostle Peter made this statement in the context of how Christ had made salvation available to us. Peter compared how Noah and his family were saved from the Flood with the New Testament process of water baptism, which serves as a symbol of faith in Jesus Christ’s death, burial and resurrection that make salvation possible (1 Peter 3:20-21).
For more about water baptism and salvation, see “Do You Have to Be Baptized to Be Saved?”