Psalm 18:16 New English Translation

¹⁶He reached down^[a] from above and took hold of me;
he pulled me from the surging water.^[b]

Psalm 18:16 tn Heb “stretched.” Perhaps “his hand” should be supplied by ellipsis (see Ps 144:7). In this poetic narrative context the three prefixed verbal forms in this verse are best understood as preterites indicating past tense, not imperfects.
Psalm 18:16 tn Heb “mighty waters.” The waters of the sea symbolize the psalmist’s powerful enemies, as well as the realm of death they represent (see v. 4 and Ps 144:7).

New English Translation (NET)