Peter speaks in 2 Peter 3 of a coming/day of the Lord/day of God where the heavens and earth will be destroyed and replaced by a new heaven and earth. In a previous post, I laid the groundwork for concluding that this day of the Lord is not the return of Jesus at the end of time because the objection from mockers was that this coming had been anticipated since the time of their ancestors (v. 4). (A length of time Peter also alludes to in v. 8-9). This couldn’t be the return of Jesus since these ancestors lived before Christ’s first appearance on earth. (They wouldn’t be anticipating His return if He hadn’t made His first appearance!) In this post, let me develop what I do think Peter is speaking of.

4. About five centuries before, Malachi had spoken of a day of the Lord that would come upon the Jewish nation. Chapters 3 & 4 speak to this. This day was to be preceded by a “messenger, who will prepare the way before me” (3:1). He is also referred to as “Elijah” (4:5). If the Jewish people failed to listen to him, God said, “I will come and strike the land with total destruction” (v. 6). In Matthew 17:13, “Elijah” is identified as John the Baptist. Jesus said that the Jewish people “did not recognize him, but have done to him everything they wished” (v. 12). Therefore, judgment was coming to them and occurred in AD 70 when the Romans under Titus, destroyed Jerusalem and the temple. I think this is the judgment that Peter is alluding to in 2 Peter 3.
5. In both the judgment of the flood and on Jerusalem what was destroyed was not the earth itself, but the world of the ungodly.
The earth was covered in water, but it wasn’t destroyed in any meaningful sense of the word. What was destroyed was the world of the ungodly. This is what will happen to the “present heavens and earth” in the judgment upon the ungodly of Jerusalem (3:7). As with the flood, it is an act of uncreation. If creation is a blessing to man, then uncreation is a curse. 6. The “new heaven and earth” (v. 13), is the language of blessing and refers to an existence apart from such evildoers, i.e., “the home of righteousness.” This is the same kind of imagery that is employed by John in Revelation 20-21. After the devil, the beast and the false prophet (the latter two representing Rome under Domitian), have been thrown into the lake of fire, earth and sky (heaven) flee. Why? “There was no place for them” (20:11). Their world had been judged by God and it was no more. What “replaces” it? A new heaven and earth (world) where Rome no longer brought any more death, mourning, crying, or pain, because “the old order of things has passed away” (v. 4).
If you have never read 2 Peter 3 this way, it can definitely be a little mind bending at first. However, it you stick with this and work through it, I think you’ll find that this understanding meshes with both the immediate context of 1 & 2 Peter as well as the overall flow of the biblical story. You might be interested in this on 1 Peter 4:7.