King James Bible
Whereby the world that then was, being overflowed with water, perished:

New King James Version
by which the world that then existed perished, being flooded with water.

American Standard Version
by which means the world that then was, being overflowed with water, perished:

Berean Study Bible
through which the world of that time perished in the flood.

Douay-Rheims Bible
Whereby the world that then was, being overflowed with water, perished.

English Revised Version
by which means the world that then was, being overflowed with water, perished:

World English Bible
by which means the world that then was, being overflowed with water, perished.

Young's Literal Translation
through which the then world, by water having been deluged, was destroyed;

2 Peter 3:6 Additional Translations ...