Genesis 7:18

Gen 7:18 And the waters prevailed, and were increased greatly upon the earth; and the ark went upon the face of the waters.

Ver. 18. And the ark went upon the face of the waters.] Where now were those profane scoffers that asked what the old fool meant to build such a vessel? and whether, when he had made his ship, he would also make a sea for it to swim in?

John Trapp, A Commentary or Exposition upon All the Books of the Old and New Testament (1647–1656) — public domain. Text from a community e-Sword module.

Fifteen cubits upwards did the waters prevail,.... Either to such an height above the earth, upwards from that, or from the high hills; for though the words do not necessarily imply that, yet it may be allowed, since there was water enough to cover the highest of them; and fifteen cubits of water were enough to drown the tallest man, or largest beast that should be upon the top of any of them:

and the mountains were covered, with water, even it may be allowed fifteen cubits high; nor will this furnish out so considerable an objection to the history of the flood as may be thought at first sight, since the highest mountains are not near so high as they are by some calculated. Sir Walter Raleigh allows thirty miles for the height of the mountains, yet the highest in the world will not be found to be above six direct miles in height. Olympus, whose height is so extolled by the poets, does not exceed a mile and a half perpendicular, and about seventy paces. Mount Athos, said to cast its shade into the isle of Lemnos (according to, Pliny eighty seven miles) is not above two miles in height, nor Caucasus much more; nay, the Peak of Teneriff, reputed the highest mountain in the world, may be ascended in three days (according to the proportion of eight furlongs to a day's journey), which makes about the height of a German mile perpendicular; and the Spaniards affirm, that the Andes, those lofty mountains of Peru, in comparison of which they say the Alps are but cottages, may be ascended in four days' compass (o).

(o) See the Universal History, vol. 1. p. 218. marg. Bedford's Scripture Chronology, ch. 12. p. 152, 153.

John Gill's Exposition of the Whole Bible (1746–1763) — public domain (CC PDM 1.0). Text via the HelloAO Bible API.

The waters were increased greatly upon the earth; overthrowing men, and houses, and trees, where possibly they did or thought to secure themselves.

Matthew Poole's English Annotations on the Holy Bible (1683–1685) — public domain. Text from a community e-Sword/MySword module.

ויגברו [AND THE WATERS] PREVAILED — by themselves (without any external aid).

Rashi on the Tanakh — English translations: “The Judaica Press complete Tanach with Rashi, translated by A. J. Rosenberg” (CC BY 4.0); “Pentateuch with Rashi's commentary by M. Rosenbaum and A.M. Silbermann, 1929-1934” (public domain); “The Metsudah Tanach series, Lakewood, N.J” (CC BY 4.0); and “The Book of Joshua, Metsudah Publications, 1997” (CC BY 4.0). Text via Sefaria.

AND THE WATERS PREVAILED (‘Vayigb’ru’). AND THE WATERS ‘GAVRU’ (PREVAILED). This means that they increased exceedingly, for the Hebrew language calls great abundance gvurah (strength, power). So too, And their transgressions which ‘yithgavru’ (have prevailed), meaning increased exceedingly; His mercy ‘gavar’ (has prevailed) toward them that fear Him, meaning increased. And so also: If ‘bigvuroth’ four-score years, 90:10. meaning with great abundance.It is conceivable that the meaning of vayigb’ru is that the rains came in a rushing downpour, uprooting trees and toppling buildings, since power is called in Hebrew gvurah (strength) because strength lies in power. In a similar sense are the verses: They also ‘gavru’ (wax mighty) in power; ‘Vehigbir brith’ (And he shall make a strong covenant) with many for one week, meaning he will establish the covenant with firmness. And in the words of the Sages, [we find the expression], gvuroth geshamim (the powers of the rains), because they come down with strength. It is possible that the verse, If ‘bigvuroth’ four-score years, 90:10. is of the same sense, i.e., if his bones and body be strong, and he is a man of power, he will live four-score years. And if so, ‘gavru’ upon the earth will mean that the waters were in their complete strength, overcoming even the high mountains and inundating them.

Ramban (Nachmanides) on the Tanakh — English translation: “Commentary on the Torah by Ramban (Nachmanides). Translated and annotated by Charles B. Chavel. New York, Shilo Pub. House, 1971-1976” (CC BY 4.0). Text via Sefaria.

ויגברו המים, this verse adds a new dimension to what we have been told already, i.e. that the waters became turbulent. This is why the Torah adds the word מאד מאד twice, something most unusual. The repeated statement וירבו, that the waters still kept increasing in volume, is meant to tell us that the waters did not only increase in turbulence but also kept increasing in quantity. Whereas originally, the waters could only raise the ark, now, thanks to the turbulence, the ark was driven in different directions from where it had stood originally.

Radak on the Tanakh — English translations: “Sefaria Community Translation” (CC0 1.0 (public-domain dedication)); “Eliyahu Munk, HaChut Hameshulash” (CC BY 4.0); “Rabbi Mike Feuer, Jerusalem Anthology” (CC BY 4.0); and “R. David Kimhi on the first book of Psalms, Translated by R.G. Finch, London, 1919” (public domain). Text via Sefaria.