Psalms 104:8

“They go up by the mountains, they go down by the valleys, etc.] The Targum is, “they ascend out of the deep to the mountains;” that is, the waters, when they went off the earth at the divine orders, steered their course up the mountains, and then went down by the valleys to the place appointed for them; they went over hills and dales, nothing could stop them or retard their course till they came to their proper place; which is another instance of the almighty power of the Son of God. Some render the words, “the mountains ascended, the valleys descended f1447”; and then the meaning is, when the depth of waters were called off the earth, the mountains and valleys appeared, the one seemed to…”

“They go up by the mountains ... - That is, when they were gathered together into seas. They seemed to roll and tumble over hills and mountains, and to run down in valleys, until they found the deep hollows which had been formed for seas, and where they were permanently collected together. The margin here is, “The mountains ascend, the valleys descend.” So it is translated in the Septuagint, in the Latin Vulgate, by Luther, and by DeWette. The more natural idea, however, is that in our translation: “They (the waters) go up mountains; they descend valleys.” Unto the place - The deep hollows of the earth, which seem to have been scooped out to make a place for them. Which thou hast founded for…”

“Go up - In that first division of the waters from the earth, part went upwards, and became springs in the mountains, the greatest part went downwards to the channels made for them. Psalms 104:9”

“104:8 The earth originates in God’s will.”

“They go up: etc. or, The mountains ascend, the valleys descend, Gen 8:5 Psalms 104:9”

“Psa 104:8 continues with the words אל־מקום (cf. Gen 1:9, אחד אל־מקום): the waters retreat to the place which (זה, cf. Psa 104:26, for אשׁר, Gen 39:20) God has assigned to them as that which should contain them. He hath set a bound (גּבוּל, synon. חק, Pro 8:29; Jer 5:22) for them beyond which they may not flow forth again to cover the earth, as the primordial waters of chaos have done. Psalms 104:10”