According to Rav Saadya Gaon (commentary to Genesis 9:13) the rainbow was not a new phenomenon. Rather it was imbued with new meaning as the sign of the covenant.
Similarly, Ramban, writes (commentary to Genesis 9:12) that although the simple reading of the verses indicates it was a new phenomenon, we are forced to accept the conclusion of the Greeks that ...
There are several reasons as pointed out by Rav Sorotzkin, Rav Hirsch and others.
First of all, they could not have stored sufficient food to last for the entire flood. The flood lasted for an entire solar year. In fact, it was only by a miracle that Noach and the animals had sufficient food during the flood and while they were repopulating the Earth.
Rav Hirsch writes on Noach 9:12
It is by no means necessary to assume that hitherto there had been
no rainbow and to place it in connection with the atmospheric changes
which occurred after the Flood. Just as Hashem showed Avraham the
starry heavens and said, כה יהיה זרעך, as He showed Moshe and Aharon
the new moon, and with the words החדש הזה לכם ...
Apparently, 2 cockroaches were on the ark. Breishit (Gen.) 6:20 mentions "all that crawls on the land". I would include insects in that category.
Apparently, they made it out of the ark alive, too as Breishit 8:17 implies. Miraculous that the elephants didn't squash them and the cats didn't eat them :-)
R' Aryeh Kaplan z'l teaches as follows:
R' Nehunia ben Hakana brings in Sefer Temuna that there are larger shmita cycles of 7000 years each, of which we are now in the 6th, putting the age of the earth at 42,000 years old.
Midrash states that a "Divine day" is like 1000 years. Therefore a "Divine year" is 365,250 years.
R' Yitzchak of Acco - who ...
Their own stubbornness. (As Monica said in a comment.)
Note similarly in Exodus, Moses warns the Egyptians that anyone/anything left outside will be stricken by hailstones. Some Egyptians are willing to at least consider this possibility, and move their slaves and cattle inside. But a lot of the Egyptians are too proud to even openly acknowledge that they ...
The Yalkut Shimoni to Ester (1056) states the God preserved the ark (or at least part of it) as a remembrance of the deluge for future generations, and Haman's son sent him a 50 cubit beam from it which he used for the gallows intended for Mordekhai:
יעשו עץ גבוה חמשים אמה והיה המן חוזר ומבקש קורה של חמשים אמה ולא מצאה, אלא קורה שהיתה בתוך ביתו לפי שהיה ...
10 righteous people (or 9, rounding up) were required to prevent the destruction of humanity. Noach and crew were only 8, therefore they could not save the world. Clearly, by the standard that G-d was using to judge righteousness, no one else in the world was considered righteous.
This number can be found in Rashi, Bereishis 18:32:
אולי ימצאון שם עשרה. ...
R Ari Wasserman explains the ark was a "chesed school" and that feeding animals became the mechanism to teach Noah and his family a value which would be fundamental to the new world being created.
As Chazal tell us, feeding all these creatures was a full-time,
round-the clock job, as some were nocturnal, some ate more often than
others, etc. Noach and ...
Rashi to Genesis 7:4 explains that it's because of their sin of adultery:
ארבעים יום. כְּנֶגֶד יְצִירַת הַוָּלָד, שֶׁקִּלְקְלוּ לְהַטְרִיחַ לְיוֹצְרָם לָצוּר צוּרַת מַמְזֵרִים
"Forty days" – corresponding to the formation of the fetus, for their sins troubled their Creator to form the form of children of illicit relations.
Rashi here refers to a ...
Rabbi Sorotzkin in Oznayim Latorah (Insights to the Torah) says that Noach continued to feed all the animals for the year after they left the teivah. In Noach 8:17, Hashem gives a bracha which includes the term שרצו which implies increasing like the "creeping things" (such as insects). Thus, Rabbi Sorotzkin says that immediately upon leaving the ark they ...
Rambam discusses the beginnings of idolatry in Hilchot Avodat Kochavim 1:1-2
בימי אנוש טעו בני האדם טעות גדול ונבערה עצת חכמי אותו הדור ואנוש עצמו
מן הטועים היה וזו היתה טעותם אמרו הואיל והאלהים ברא כוכבים אלו וגלגלים
להנהיג את העולם ונתנם במרום וחלק להם כבוד והם שמשים המשמשים לפניו
ראויין הם לשבחם ולפארם ולחלוק להם כבוד וזהו רצון האל ברוך הוא לגדל
For Ch. 6:17 the Torah Sheleimah Vol 2 page 408 note 198 brings the Medrash Raba that VaYigva here means to shrivel.
For Ch. 7:21 the Torah Sheleimah Vol 2 page 429 note 79 brings the question and an answer based on the manuscript version of Bava Basra 16b:
Only when the Torah uses the terms Geviya and Asifa does it refer to a righteous [painless] death.
Ramban (Chapter 9, Verse 12) argues that the rainbow existed before the Mabul. However, only after the Mabul did Hashem select it to serve as a sign of His covenant to not cause another Mabul. The rainbow is a reversed bow. One who wishes to indicate peaceful intentions reverses his weapon away from the person he is greeting and points the weapon towards ...
Ravina himself asks this question to R. Hama Bar Buzi who suggested this, as recorded in Bava Batra (16b). Rav Hama bar Buzi answered that we only say this when the term gevia and asifa are both used. In the case of the flood, the term asifa is not used.
Rabbi Shimshon Refael Hirsch on Noach 10:1 (translation is from the 6 volume Hirsch Chumash)
And these are the "toldos" of the sons of Noach, Shem Cham, and Yafes,
Unto them children were born after the deprivation of life.
They themselves had lived before the Flood, but their children were
already born under the influence of the new ...
Ralbag in his commentary to the Flood Narrative writes as follows:
והנה השלים זה הסיפור והפליג להאריך בו לרוב התועלת המגיע ממנו ולזה דקדק
במספר הימים אשר ירד הגשם בלי הפסק ובשאר הפרטים לישב יותר בלבנו אמיתת
זה הסיפור כי כבר נאמין יותר בספורים כשיסופר מענינם פרטים רבים
And behold it completed this narrative and elaborated on
it extensively due ...
The Moshav Z'keinim (Breishis 25:27) writes that the year in the teiva wasn't reckoned in Noach's age because the natural order of the universe wasn't functioning.
אלא שנה שהיו בתיבה לא חשיב לפי שלא שמשו סדרי בראשית
Fish were not harmed:
the Gemara notes that marine life was not harmed by the Mabul.
(Sanhedrin 108a, quoted by Rashi on Bereshis 7:22)
that were on the dry land: But not the fish, which were in the sea. — [Sanh. 108a]
Maharsha says that only the water that covered the land was boiling hot. Others say that a cone of water under the ark was prepared to ...
Ibn Ezra to Bereishis 6:20 says that if someone would suggest that some animals needed to be fed with meat in the teiva this would be dismissed as a valid question because even one who cannot find meat would eat grass and fruits when it is starving or hungry.
Rabbi Meiselman's book "Torah, Chazal and Science" addresses the concept of a local flood (p.556 heading 'A local deluge'):
In the early 20th century the observant community of Germany was an
integral part of the surrounding intellectual world. Consequently, the
challenges posed by modern thought and research were grequent subjects
of discussion. ...
In Pirkei Derabbi Eliezer 23 it says that Og was the only survivor of the flood other than Noach and his family (and animals) as he hanged on to a ladder:
וימח את כל היקום אשר על פני האדמה חוץ מנח וכל אשר אתו בתבה שנאמר וישאר אך נח ואשר אתו בתבה וחוץ מעוג מלך הבשן שישב לו עץ אחד מן הסולמות של התיבה ונשבע לנח ולבניו שיהיה להם עבד עולם מה עשה נח נקב חור אח' ...
Ohr Hachayim Noach 6,10 and 7,1 discusses this. It appears that minors can pass on due to parental sins. it was only because of Noach's righteousness that they were saved in his merit (as minors). It is unclear if this is the case only with bnai-Noach or also with Yisroel. Later, he indicates that Noach's children were saved because in Noach's merit they ...
Chiddushei Agadot on Zevachim 113b suggests that the boiling waters only occurred where it was covering previously dry land. To wit, waters that predated the Flood (i.e. the various bodies of water) - which contained sea life - were not subjected to the boiling temperatures in keeping with the notion that sea life was unaffected as they had not become ...
Ralbag explains that Noah brought seeds with him on the ark to replant the world afterwards, and he provides three reasons why the Torah doesn't mention this:
וראוי שתדע שמיני הצמחים אשר יתכן הפסדם מפני המבול השגיח השם ג"כ בהם בזה האופן ששם נח מהזרעים ההם בתיבה בדרך שישאר מהם לזרע בארץ אחר המבול ולא זכרה זה התורה בביאור לפי שהרבה מהצמחים לא נצטרכו אל ...
The animals before and after the flood were also all vegetarian. They only started to eat meat after the flood. Also, since the food supply in the ark was miraculous, Noach probably had a miraculous type of food (like the mannah in the dessert) that suited each animal as it needed. As we see in Bereishis 1:30
ל וּלְכָל חַיַּת הָאָרֶץ וּלְכָל עוֹף ...