Augustine of Hippo

"He gathers the waters of the sea together as into a bottle:" He gathered the people of the world together, to confession of mortified sin, lest through pride they flow too freely. "He lays up the deep in storehouses" [Psalm 33:7]: and keeps in them His secrets for riches.

Exposition on Psalm 33 ↗

Thomas Aquinas

Then when he says, "Gathering together the waters of the sea as in a vessel," he shows the effect of God in the waters. In the waters, two wondrous things are to be considered. One is that the waters are gathered into one part of the earth and do not occupy the entire surface, which is wondrous for two reasons. First, because the natural order is that water should surround the whole earth, just as air surrounds water. Likewise, the sea is higher than the earth. …

Exposition on the Psalms of David ↗

Bonaventure

Concerning the gathering of waters, the Psalm says: "He gathers the waters of the sea as in a flask." He gathers the waters of the sea in a flask when He brings together in the skin of Scriptures the totality of the spiritual meanings. Now there are three reasons why these meanings are compared to waters gathered in a wine-bag — to wit, because of the primitive origination of these spiritual meanings, because of their most profound depth, and because of their abundantly flowing multiformity.

Collations on the Hexaemeron, Collation 13 ↗