Our Gemara on Amud Aleph tells us that the fate of the Generation of the Flood came about in response to their behavior:

They sinned with boiling heat, and they were punished with boiling heat; and they were punished with the boiling heat of scalding waters.

What was the sin of boiling heat?  Presumably the sin of lust, as is implied from Sanhedrin (108b).  Tzidkas HaTzaddik ( צדקת הצדיק ק״ז:א׳ ) makes a point that if you remove the Godly part between a man and woman, which in Hebrew represents the letter Hey, the remaining letters spell Eish, fire.  Thus, in effect, they brought it upon themselves.

Be'er Mayim Chaim Bereishis (6:17) asks, if so, why not fire instead of a flood?  He answers, it would not have been possible for Noach to escape in an ark if there was fire, so therefore Hashem brought a flood, but with scalding waters.  Somehow, this peshat feels lacking.  After all, could not God have come up with some idea for Noach?  Perhaps teach him to build a rocket ship or something?

I think we must conclude that scalding water has a different essence and message than fire. Fire completely breaks down and destroys what is in its path, while hot water cooks and transforms, though of course could also be deadly, can also be transformative. Therefore, scalding waters are a more fitting metaphor for sexual passion as it can be transformative or deadly, depending on how you use it.

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Translations Courtesy of Sefaria, (except when, sometimes, I disagree with the translation cool.)