They go up by the mountains; they go down by the valleys unto the place which thou hast founded for them.
They go up by the mountains; they go down by the valleys. The waters, tumultuously excited by God's "rebuke" after having been brought down by it, again 'go up TO the mountains,' whence they had been dislodged; but being unable to keep themselves there, 'they go down to the valleys,' until they at length settle down in the place assigned to them by God. Compare Psalms 107:26; Genesis 1:9, God said, "Let the waters under the heaven be gathered together unto one place, and let the dry land appear, and it was so." The appearing of the dry land, not its formation, was the work of the third day.
Unto the place which thou hast founded for them. God, as the Master-Builder, founded the deep bed of the sea as the receptacle for the waters and their countless inhabitants (Psalms 104:5; Psalms 104:25; Psalms 102:25).