Albert Barnes Commentary Psalms 18:16

"He sent from on high, he took me; He drew me out of many waters." — Psalms 18:16 (ASV)

He sent from above - He interposed to save me. All these manifestations of the divine interposition were from above, or from heaven; all came from God.

He took me - He took hold of me; he rescued me.

He drew me out of many waters - Margin, "great waters." Waters are often expressive of calamity and trouble (Psalms 46:3; Psalms 69:1; Psalms 73:10; Psalms 124:4–5). The meaning here is that God had rescued him out of the many troubles and dangers that encompassed him, as if he had fallen into the sea and was in danger of perishing.