Through translates the same preposition rendered “by means of” in verse 5. Which is a plural relative pronoun and can be interpreted in many ways, three of which are worth mentioning:
1. It goes back to “word” in verse 5. This makes verses 5, 6, and 7 structurally parallel: heaven and earth were created, the world was destroyed by water, and all creation will be destroyed by fire, all by means of God’s word. However, the plural form of the Greek for which argues against this position.
2. It refers to both “word” and “water.” These three verses will then be structurally connected thus: word and water (verse 5), word and water (verse 6), word and fire (verse 7).
3. It refers to “water.” The plural form can either refer to the two types of water (water above and water below the heavens) from which the flood had come (Gen 7.11), or be taken as a Hebrew idiom, since in Hebrew, water, like heaven, is usually plural in form.
This third possibility is the choice of by far the most translations. There is a need, however, to restructure the verse because of the mention of water in the second half (through which [water] the world … was deluged with water and perished), which makes the sentence somewhat awkward. A possible way of resolving this problem is to identify “water” in the first part of the verse with “water” in the second part, which is what Good News Translation has done (“and it was also by water, the water of the flood, that the old world was destroyed”). We may also translate “and God also used water, the water of the flood, to destroy the old world.”
World translates the Greek word kosmos, the world of order and harmony, as contrasted with the pre-creation state of chaos and disorder. The world that then existed (Good News Translation “the old world”) is taken by many commentaries as referring to the whole universe, which includes both heaven and earth; this stresses the cosmic scope of the great flood, affecting not only earth but heaven as well. It is more likely, however, that in the present context world refers only to the inhabited earth and human beings in particular. Since the earth is formed by means of water, it can also be destroyed in the same way. In certain languages the Revised Standard Version rendering world that then existed (New Revised Standard Version “world of that time”) will be preferable to that of Good News Translation “the old world.” However, we may also translate “that world long ago.”
Deluged is literally “flooded”; the whole expression refers to the great flood recorded in Genesis 6-8. Perished is more naturally “was destroyed” (Good News Translation), since the whole physical universe together with its inhabitants can be destroyed, whereas only living beings, and more especially human beings, can be described as perishing. The destruction here is primarily viewed in terms of being submerged in water, that is, the ordered universe (the kosmos) goes back to its original chaotic state (see Gen 1.1-2).
It should be noted that in the Genesis account of the flood (chapters 6-8) it is not the earth that was destroyed but human beings and other living things. Here the focus is on the whole earth and not simply human beings and other living things. It is true, of course, that the destruction of living things has the effect of putting the earth into a very chaotic state. However, translators should translate the picture here rather than going back to the Genesis account.
Quoted with permission from Arichea, Daniel C. and Nida, Eugene A. A Handbook on The Second Letter from Peter. (UBS Handbook Series). New York: UBS, 1980. For this and other handbooks for translators see here .