As the waters fail from the sea - As the waters evaporate wholly, and leave the bottom wholly dry, so it is with man, who passes entirely away, and leaves nothing. But to what fact Job refers here, is not known. The sea or ocean has never been dried up, so as to furnish a ground for this comparison. Noyes renders it, "the lake." Dr. Good, without the slightest authority, renders it, "as the billows pass away with the tides." Herder supposes it to mean that until the waters fail from the sea man will not rise again, but the Hebrew will not bear this interpretation. Probably the true interpretation is, that which makes the word rendered sea (ים yâm) refer to a lake, or a stagnant pool; see Isaiah 11:15, note; Isaiah 19:5, note. The word is applied not unfrequently to a lake, as to the lake of Genesareth, Numbers 34:11; to the Dead Sea, Genesis 14:3; Deuteronomy 4:49; Zac 14:8. It is used, also, to denote the Nile, Isaiah 19:5, and the Euphrates, Isaiah 27:1. It is also employed to denote the brass sea that was made by Solomon, and placed in front of the temple; 2-Kings 25:13. I see no reason to doubt, therefore, that it may be used here to denote the collections of water, which were made by torrents pouring down from the mountains, and which would after a little while wholly evaporate.
And the flood decayeth - The river - נהר nâhâr. Such an occurrence would be common in the parched countries of the East; see the notes at Job 6:15 ff. As such torrents vanish wholly away, so it was with man. Every vestige disappeared; compare 2-Samuel 14:14.

The waters fail from the sea - I believe this refers to evaporation, and nothing else. As the waters are evaporated from the sea, and the river in passing over the sandy desert is partly exsiccated, and partly absorbed; and yet the waters of the sea are not exhausted, as these vapors, being condensed, fall down in rain, and by means of rivers return again into the sea: so man is imperceptibly removed from his fellows by death and dissolution; yet the human race is still continued, the population of the earth being kept up by perpetual generations.

As the waters fail from the sea,.... the words may be rendered either without the as, and denote dissimilitude, and the sense be, that the waters go from the sea and return again, as with the tide:
and the flood decays and dries up; and yet is supplied again with water: "but man lieth down, and riseth not again", Job 14:12; or else with the as, and express likeness; as the waters when they fail from the sea, or get out of lakes, and into another channel, never return more; and as a flood, occasioned by the waters of a river overflowing its banks, never return into it more; so man, when he dies, never returns to this world any more. The Targum restrains this to the Red sea, and the parting of that and the river Jordan, and the drying up of that before the ark of the Lord, and the return of both to their places again.

sea--that is, a lake, or pool formed from the outspreading of a river. Job lived near the Euphrates: and "sea" is applied to it (Jeremiah 51:36; Isaiah 27:1). So of the Nile (Isaiah 19:5).
fail--utterly disappeared by drying up. The rugged channel of the once flowing water answers to the outstretched corpse ("lieth down," Job 14:12) of the once living man.

As - So it is with man. Or thus, as when the waters fail from the sea, when the sea forsakes the place into which it used to flow, the river which was fed by it, decayeth and drieth up without all hopes of recovery.