The voice of the Lord, i.e. thunder, as is manifest from the next clause, and the following effects; which is oft called the Lord's voice, as Exodus 9:23,28,29 Job 37:4,5 Psa 18:14 46:6. Upon the waters; either, 1. Upon the seas; where its noise spreads far and wide, and is very terrible. But the following verses speak of the effects of it upon the earth only. Or rather,
2. Above in the clouds, which are called waters, Genesis 1:7 Psalms 18:11, because they are of a watery substance. And this circumstance is considerable here, to magnify the Divine power, which displayeth itself in those high places, which are far above the reach of all earthly potentates, and from whence he can easily and unavoidably smite all that dwell upon the earth, and will not submit to him. Upon many waters, i.e. upon the clouds, in which there are vast treasures of water, and upon which God is said to sit or ride, Psalms 18:10,11 Psalms 104:3.