Genesis 7:20 - Flood's height: Divine measure?

Verse Context: The Flood Waters in Noach's Time

The verse (Bereishit 7:20) describes the height of the floodwaters during the mabul (great flood) in the time of Noach. The waters rose fifteen cubits above the highest mountains, covering them entirely. This demonstrates the totality of the destruction, as even the tallest peaks were submerged.

Measurement of Fifteen Cubits

Rashi explains that the fifteen cubits measurement is significant because the ark itself was thirty cubits tall (Bereishit 6:15). The floodwaters rose fifteen cubits above the highest mountains, meaning the ark floated with half its height submerged and half above water—fifteen cubits each way. This ensured the ark would not scrape against mountain peaks as it floated.

Divine Precision in Judgment

The Ramban (Nachmanides) notes that the floodwaters did not merely cover the mountains but exceeded them by a precise measure. This reflects Hashem's exact justice—enough to destroy the corrupt generation but no more than necessary. The number fifteen may also allude to the fifteen words in the first half of Az Yashir (Shemot 15:1), symbolizing divine salvation emerging from judgment.

Midrashic Insights

• Midrash Tanchuma connects the fifteen cubits to the fifteen steps in the Beit Hamikdash (upon which the Levites sang), suggesting a contrast between destruction and future redemption.
• Pirkei D'Rabbi Eliezer teaches that the waters rose gradually over forty days, allowing time for repentance—though the generation ignored this mercy.

Symbolism of Water Covering Mountains

The Talmud (Sanhedrin 108a) states that the floodwaters erased even the elevated places where idolatry was practiced, emphasizing the thoroughness of the purification. The Zohar adds that the waters rose to cleanse the spiritual impurity of the generation, whose sins had "reached the heavens" (Bereishit 6:11).