John Gill Commentary Psalms 33:7

"He gathereth the waters of the sea together as a heap: He layeth up the deeps in store-houses." — Psalms 33:7 (ASV)

He gathereth the waters of the sea together as an heap
Which was done on the third day of the creation, by means of which the dry land appeared, (Genesis 1:9Genesis 1:10); when the waters of the sea were piled up as an heap, and stood higher than the earth, as they now do; and which is a wonderful instance of the power and providence of God, to bound them, and preserve the earth from being overflowed by them, (Job 38:9–11);

he layeth up the depth in storehouses ;
that is, large quantities of water, for which he has his treasure houses, as for the wind, hail and snow, (Psalms 135:7) (Job 38:16Job 38:22); and these are the clouds of heaven above, and the fountains of the great deep below, which the Lord opens and stops at his pleasure; see (Genesis 7:11) (8:2) .