Genesis 7:18

the waters increased, and bare up the ark--It seems to have been raised so gradually as to be scarcely perceptible to its occupants.

We are here told,
I. How long the flood was increasing - forty days, Gen 7:17. The profane world, who believed not that it would come, probably when it came flattered themselves with hopes that it would soon abate and never come to extremity; but still it increased, it prevailed. Note, 1. When God judges he will overcome. If he begin, he will make an end; his way is perfect, both in judgment and mercy. 2. The gradual approaches and advances of God's judgments, which are designed to bring sinners to repentance, are often abused to the hardening of them in their presumption.
II. To what degree they increased: they rose so high that not only the low flat countries were deluged, but to make sure work, and that none might escape, the tops of the highest mountains were overflowed - fifteen cubits, that is, seven yards and a half; so that in vain was salvation hoped for from hills or mountains, Jer 3:23. None of God's creatures are so high but his power can overtop them; and he will make them know that wherein they deal proudly he is above them. Perhaps the tops of the mountains were washed down by the strength of the waters, which helped much towards the prevailing of the waters above them; for it is said (Job 12:15), He sends out the waters, and they not only overflow, but overturn, the earth. Thus the refuge of lies was swept away, and the waters overflowed the hiding-place of those sinners (Isa 28:17), and in vain they fly to them for safety, Rev 6:16. Now the mountains departed, and the hills were removed, and nothing stood a man in stead but the covenant of peace, Isa 54:10. There is no place on earth so high as to set men out of the reach of God's judgments, Jer 49:16; Oba 1:3, Oba 1:4. God's hand will find out all his enemies, Psa 21:8. Observe how exactly they are fathomed (fifteen cubits), not by Noah's plummet, but by his knowledge who weighs the waters by measure, Job 28:25.
III. What became of Noah's ark when the waters thus increased: It was lifted up above the earth (Gen 7:17), and went upon the face of the waters, Gen 7:18. When all other buildings were demolished by the waters, and buried under them, the ark alone subsisted. Observe, 1. The waters which broke down every thing else bore up the ark. That which to unbelievers is a savour of death unto death is to the faithful a savour of life unto life. 2. The more the waters increased the higher the ark was lifted up towards heaven. Thus sanctified afflictions are spiritual promotions; and as troubles abound consolations much more abound.

And the flood was forty days , etc. Moses copiously insists upon this fact, in order to show that the whole world was immersed in the waters. Moreover, it is to be regarded as the special design of this narrations that we should not ascribe to fortune, the flood by which the world perished; how ever customary it may be for men to cast some veil over the works of God, which may obscure either his goodness or his judgments manifested in them. But seeing it is plainly declared, that whatever was flourishing on the earth was destroyed, we hence infer, that it was an indisputable and signal judgment of God; especially since Noah alone remained secure, because he had embraced, by faith, the word in which salvation was contained. He then recalls to memory what we before have said; namely how desperate had been the impiety, and how enormous the crimes of men, by which God was induced to destroy the whole world; whereas, on account of his great clemency, he would have spared his own workmanship, had he seen that any milder remedy could have been effectually applied. These two things, directly opposed to each other, he connects together; that the whole human race was destroyed, but that Noah and his family safely escaped. Hence we learn how profitable it was for Noah, disregarding the world, to obey God alone: which Moses states not so much for the sake of praising the man, as for that of inviting us to imitate his example. Moreover, lest the multitude of sinners should draw us away from God; we must patiently bear that the ungodly should hold us up to ridicule, and should triumph over us, until the Lord shall show by the final issue, that our obedience has been approved by him. In this sense, Peter teaches that Noah's deliverance from the universal deluge was a figure of baptism, (1 Peter 3:21;) as if he had said, the method of the salvation, which we receive through baptism, degrees with this deliverance of Noah. Since at this time also the world is full of unbelievers as it was then; therefore it is necessary for us to separate ourselves from the greater multitude, that the Lord may snatch us from destruction. In the same manner, the Church is fitly, and justly, compared to the ark. But we must keep in mind the similitude by which they mutually correspond with each other; for that is derived from the word of God alone; because as Noah believing the promise of God, gathered himself his wife and his children together, in order that under a certain appearance of death, he might emerge out of death; so it is fitting that we should renounce the world and die, in order that the Lord may quicken us by his word. For nowhere else is there any security of salvation. The Papists, however, act ridiculously who fabricate for us an ark without the word.

Footnotes:

[276] Le Clerc objects to this interpretation, and supposes that seven of each sex, of unclean animals, were admitted into the ark. Perhaps a skeptical objection to the use of the seventh animal, as a sacrifice, inclined him to adopt this interpretation. Commentators, however, have generally preferred the solution here given. -- Ed.

The Lord shut him in - This seems to imply that God took him under his especial protection, and as he shut Him in, so he shut the Others out. God had waited one hundred and twenty years upon that generation; they did not repent; they filled up the measure of their iniquities, and then wrath came upon them to the uttermost.

And the waters prevailed, and were increased greatly upon the earth,.... Still they became greater and more powerful, as to bear up the ark, so to cast down houses, trees, &c. by the continual rains that fell, though perhaps they were not so violent as before, and by the constant eruptions of water out of the earth:

and the ark went upon the face of the waters; it floated about upon them, in an easy gentle manner; for there were no storms of wind or tempests raised, which might endanger it. (If much of the water came from volcanic activity, and if earthquakes accompanied the breaking forth of the fountains of the deep, many tidal waves would result. This would completely destroy and remains of the old civilisation and as well give the ark a rough sea to drift in. The ark's dimensions would give make it almost impossible to upset. Ed.)

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

Gen 7:17-24 contain a description of the flood: how the water increased more and more, till it was 15 cubits above all the lofty mountains of the earth, and how, on the one hand, it raised the ark above the earth and above the mountains, and, on the other, destroyed every living being upon the dry land, from man to cattle, creeping things, and birds. "The description is simple and majestic; the almighty judgment of God, and the love manifest in the midst of the wrath, hold the historian fast. The tautologies depict the fearful monotony of the immeasurable expanse of water: omnia pontus erant et deerant litera ponto." The words of Gen 7:17, "and the flood was (came) upon the earth for forty days," relate to the 40 days' rain combined with the bursting forth of the foundations beneath the earth. By these the water was eventually raised to the height given, at which it remained 150 days (Gen 7:24). But if the water covered "all the high hills under the whole heaven," this clearly indicates the universality of the flood. The statement, indeed, that it rose 15 cubits above the mountains, is probably founded upon the fact, that the ark drew 15 feet of water, and that when the waters subsided, it rested upon the top of Ararat, from which the conclusion would very naturally be drawn as to the greatest height attained. Now as Ararat, according to the measurement of Perrot, is only 16,254 feet high, whereas the loftiest peaks of the Himalaya and Cordilleras are as much as 26,843, the submersion of these mountains has been thought impossible, and the statement in Gen 7:19 has been regarded as a rhetorical expression, like Deu 2:25 and Deu 4:19, which is not of universal application. But even if those peaks, which are higher than Ararat, were not covered by water, we cannot therefore pronounce the flood merely partial in its extent, but must regard it as universal, as extending over every part of the world, since the few peaks uncovered would not only sink into vanishing points in comparison with the surface covered, but would form an exception not worth mentioning, for the simple reason that no living beings could exist upon these mountains, covered with perpetual snow and ice; so that everything that lived upon the dry land, in whose nostrils there was a breath of life, would inevitably die, and, with the exception of those shut up in the ark, neither man nor beast would be able to rescue itself, and escape destruction. A flood which rose 15 cubits above the top of Ararat could not remain partial, if it only continued a few days, to say nothing of the fact that the water was rising for 40 days, and remained at the highest elevation for 150 days. To speak of such a flood as partial is absurd, even if it broke out at only one spot, it would spread over the earth from one end to the other, and reach everywhere to the same elevation. However impossible, therefore, scientific men may declare it to be for them to conceive of a universal flood of such a height and duration in accordance with the known laws of nature, this inability on their part does not justify any one in questioning the possibility of such an event being produced by the omnipotence of God. It has been justly remarked, too, that the proportion of such a quantity of water to the entire mass of the earth, in relation to which the mountains are but like the scratches of a needle on a globe, is no greater than that of a profuse perspiration to the body of a man. And to this must be added, that, apart from the legend of a flood, which is found in nearly every nation, the earth presents unquestionable traces of submersion in the fossil remains of animals and plants, which are found upon the Cordilleras and Himalaya even beyond the limit of perpetual snow.
(Note: The geological facts which testify to the submersion of the entire globe are collected in Buckland's reliquiae diluv., Schubert's Gesch. der Natur, and C. v. Raumer's Geography, and are of such importance that even Cuvier acknowledged "Je pense donc, avec MM. Deluc et Dolomieu, que s'il y a quelque chose de constat en gologie; c'est que la surface de notre globe a t victime d'une grande et subite rvolution, dont la date ne peut remonter beaucoup au del de cinq ou six mille ans" (Discours sur les rvol. de la surface du globe, p. 190, ed. 6). The latest phase of geology, however, denies that these facts furnish any testimony to the historical character of the flood, and substitutes the hypothesis of a submersion of the entire globe before the creation of man: 1. because the animals found are very different from those at present in existence; and 2. because no certain traces have hitherto been found of fossil human bones. We have already shown that there is no force in these arguments. Vid., Keerl, pp. 489ff.)
In Gen 7:23, instead of ויּמּח (imperf. Niphal) read ויּמח (imperf. Kal): "and He (Jehovah) destroyed every existing thing," as He had said in Gen 7:4.