See the Torah Temimah on Noah 8:1 "Vayashoku Hamayyim" that the flood waters were "boiling"
This begs the question: given that the Flood drowned all life on the dry land, why is it necessary to add "boiling" water to the mix? If it were to kill the fish - the Agaddah already tells us that the fish had been exempted from punishment anyway?
And so what value is it to US to know that the drowning waters were ALSO boiling?
I heard this d'var Torah many years ago
It was to teach US that there were TWO distinct cleansing processes at work here in order to PURIFY the earth
Immersion or T'vilah - as in a Miqveh. These drowning waters were to cleanse the earth by immersion
Hag'alah - all the impurities would be purged by boiling water - similar to kashering pots and utensils for Passover
And so we needed an Insight into how a dual cleansing works, E.G. when we need to purify ourselves or our environment