| Barnes' Notes on the Bible Upon the land. - The land is to be understood of the portion of the earth's surface known to man. This, with an unknown margin beyond it, was covered with the waters. But this is all that Scripture warrants us to assert. Concerning the distant parts of Europe, the continents of Africa, America, or Australia, we can say nothing. "All the high hills were covered." Not a hill was above water within the horizon of the spectator or of man. There were ten generations from Adam to Noah inclusive. We cannot tell what the rate of increase was. But, supposing each couple to have ten children, and therefore the common ratio to be five, the whole number of births would be about five million, and the population in the time of Noah less than four million. It is probable that they did not scatter further than the necessities and conveniences of life demanded. In a fertile region, an area equal to that of the British Isles would be amply sufficient for four million men, women, and children. Let us suppose, then, a circle of five hundred miles in diameter inhabited by man. Let this occupy the central region of a concentric circle of eight hundred miles in diameter. With a center a little southwest of Mosul, this larger circle would reach fifty miles into the Mediterranean, the Euxine, and the Caspian, and would probably have touched the Persian Gulf at the time of the deluge. If this region were covered with water, it is obvious that no land or mountain would be visible to a spectator within the inner circle of five hundred miles in diameter. "Fifteen cubits upward." This was half the depth of the ark. It may have taken this draught of water to float it. If so, its grounding on a hill under water would indicate the depth of water on its summit. The gradual rise of the waters was accomplished by the depression of the land, aided, possibly, by a simultaneous elevation of the bed of the ocean. The water, by the mere necessity of finding its level, overflowed the former dry land. The extent of this oscillation of the solid crust of the earth is paralleled by the changes of level which geology indicates, the last of which took place at the time of the six days' creation. It is possible that most of the land that was then raised was now again temporarily submerged in the returning waters; while distant continents may have all along existed, which never came within the ken of antediluvian man. The sobriety and historical veracity of the narrative are strikingly exhibited in the moderate height to which the waters are said to have risen above the ancient hills.
Gill's Exposition of the Entire BibleAnd the waters prevailed exceedingly on the earth,.... Yet more and more, so that the people without the ark were obliged to remove, not only from the lower to the higher rooms in their houses, and to the tops of them, but to the highest trees; and when these were bore down, to the highest hills and mountains; and to those it was in vain to fly, by what follows: and all the high hills that were under the whole heaven were covered: whence it appears there were hills before the flood, and that these were not caused by it, and that the deluge was universal, since there was not a hill under the whole heaven but what was covered with it. In Deucalion's flood all men are said to perish, except a few who fled to the high mountains (n); which story seems to be hammered out of this account. (n) Apollodorus, de Deor. Origin. l. 1. p. 19.
Geneva Study BibleAnd the waters prevailed exceedingly upon the earth; and all the high hills, that were under the whole heaven, were covered.
Matthew Henry's Concise Commentary7:17-20 The flood was increasing forty days. The waters rose so high, that the tops of the highest mountains were overflowed more than twenty feet. There is no place on earth so high as to set men out of the reach of God's judgments. God's hand will find out all his enemies, Ps 21:8. When the flood thus increased, Noah's ark was lifted up, and the waters which broke down every thing else, bore up the ark. That which to unbelievers betokens death unto death, to the faithful betokens life unto life.
Matthew Henry's Whole Bible CommentaryVerses 17-20 We are here told, I. How long the flood was increasing-forty days, v. 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; Obad. 3:4. God's hand will find out all his enemies, Ps. 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 (v. 17), and went upon the face of the waters, v. 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. | 
