Possible Sources for a "Regional Mabul"
[now including link to a tshuvah from R. Nadel on the Torah, geography and other continents]

1.Offered by Moshe Kaveh in this Parasha sheet;

"Views of the flood as local in scope go back to the time of the Sages. According to R. Yohanan (Zevahim 113b), the torrential rains did not fall on the Land of Israel. Likewise, the Torah Temimah commentary of Rabbi Epstein writes: "Regarding Babylonia receiving more rain than any other land in the world and being drowned by the flood, it should be noted that according to Tractate Zevahim, loc. sit., Babylon was therefore called Shinar, because all the creatures that perished in the flood were tossed (Heb. ninaru) there. It is a deep valley, and therefore is also called metzulah ('the deep')." In the mind of the Sages, Babylonia constituted the 'entire world'. This is evident in Pirkei de-Rabbi Eliezer (Horev ed., ch. 10, s.v. "be-shishi"): "... since all the creatures lived in one place, and seeing the waters of the flood, Nimrod became king over them, as it is said: 'the mainstays of his kingdom were Babylon, ...' (Gen. 10:10).""

I have many problems with this essay, particularly the use of the "Ryan-Pitman" Black Sea hypothesis, repeated misspellings of sources, and too-casual use of terms like 'scholars' and 'scientists'...but i don't know that they dilute a "regional" reading of the above sources.

2.The entire piece by Rabbi Michael Hattin from the Yeshivat Har Etzion VBM website is devoted to the issue of the 'universality' of the Mabul, and how even some of the familar statements from Chazzal (particularly Gemara and Meforshim), on the Mabul can be understood in a 'limited mabul' sense. Of particular interest is statement to the affect that;

"...Admittedly, the examples are unique and limited, but are nevertheless sufficient to force us to reconsider the thorny verses that seem to imply a universal flood that covered the entire globe and caused complete and utter destruction:

Behold, I plan to bring a flood of waters upon the earth to wipe out ALL FLESH THAT POSSESSES THE BREATH OF LIFE FROM UNDER THE HEAVENS, EVERYTHING UPON THE EARTH SHALL PERISH (6:17).

In seven days, I will cause rains to fall upon the earth for forty days and forty nights, and I will erase ALL OF CREATION THAT I HAVE FASHIONED from upon the face of the earth (7:4).

The waters rose mightily very high upon the earth, COVERING ALL OF THE HIGH MOUNTAINS THAT WERE UNDER THE HEAVENS. The waters rose to a height of fifteen cubits above, and covered all of the mountains. ALL FLESH THAT CREEPS UPON THE EARTH PERISHED – birds, beasts, animals, creatures that crawl upon the earth and ALL HUMAN BEINGS. EVERYTHING UPON DRY LAND THAT POSSESSED THE BREATH OF LIFE IN ITS NOSTRILS PERISHED. ALL OF CREATION UPON THE FACE OF THE EARTH – PEOPLE, BEASTS, CREEPING THINGS AND BIRDS OF THE SKY – WERE WASHED AWAY FROM THE EARTH. ONLY NOACH, AND THOSE THAT WERE WITH HIM IN THE ARK, REMAINED (7:19-23).

The above citations certainly seem to suggest a universal deluge that sweeps over the entire planet, unsparingly washing away everything that breathes from its surface. And yet, at least for Rabbi Yochanan, the land of Israel was spared and Og was preserved! Apparently then, expressions such as "EVERYTHING UPON DRY LAND THAT POSSESSED THE BREATH OF LIFE IN ITS NOSTRILS PERISHED " or "ALL OF CREATION UPON THE FACE OF THE EARTH…WAS WASHED AWAY FROM THE EARTH" were not understood by him in an absolutely literal sense but rather as emphatic and resounding expressions of widespread and thorough (but not necessarily universal and absolute) destruction."

3. Nosson Weisz's (possibly 'censored') piece from Aish Hatorah (may still be an unlinked page at Aish);

"God decided to wipe out all vestige of civilized man. It is curious that all the peoples surrounding the region of Mesopotamia have a flood myth as part of their cultural heritage. There is also archeological evidence of a flood that covered the entire region. There is no trace of the flood in Australia or the Americas, or any other region that was not culturally attached to the cradle of civilization.
According to the thesis presented in this essay this makes perfect sense. The flood was truly world wide, but the world referred to is the world of Adam, the civilized world. The rest of the planet was still inhabited by Stone Age man, the creature created on the sixth day along with the rest of the higher animals. That creature was never summoned to judgment, and there was no reason to destroy his world."

Also in email coorespondence, he offered several other sources for a regional event; suggesting a Rashi in Parashat Noach where Rashi quotes a gemara in Sanhedrin that asks essentially 'if people sinned, why did Hashem punish the animals?', to which the Gemara answers that they were only there for the people, imply that where people were guilty the world was destroyed - where there were no civilized people (and therefore no sinners), the world was not destroyed. He also mentioned that The Maharal often says that the wilderness is not considered "a chelek of the yishuv". I do not know that any of this remains his view on the issues per se, nor do I know that he would offer them now. I don't want to rule out the possibility that the link to his original Mayanot piece was deactivated in accord with a decision on his part - not simply due to pressure from others.

4. Rav Henkin's readings of pertinent posukim (his own translation, btw);

Translated from Commentary on the Torah "Chibah Yeteirah".
Bound together with Resp. Bnei Banim volumes 2-3, also separately.

(Bereishit 7:19). "All the high mountains were covered that are under
all of heaven." Not all mountains were covered. The word "all" (kal) is
repeated and is a ribui achar ribui and comes to limit (l'mayeit). Thus,
according to one opinion in Zevachim 113 "the flood did not descend to
Eretz Israel." This is also the implication of "the high mountains were
covered that are under all of heaven" i. e., those mountains that have all
of heaven above them, which excludes the highest mountains whose tops are
in the clouds. And similarly the implication of "that are under all of
heaven" is those [mountains of the sort] that are found everywhere, which
excludes the very high mountains that are only [found] in a few places."

5. R. Gedalyah Nadel's position as presented by R. Slifkin;

"The conventional understanding of the Torah is that the flood covered the whole planet,
based on Bereishis 7:19. But Tosafos states that the verse means no such thing. If so,
there is no reason to think that the flood covered the entire planet, just the “world” of
the Torah. This comparison was suggested to me by Rav Gedalyah Nadel z”l, who
stated that since the flood only covered the world of the Torah, which does not
include South America and Australia, it is likewise acceptable to explain that the
Torah’s list of animals with one sign is not intended to cover these areas" (pp. 40-1)