Charles Ellicott Commentary Psalms 42:7

"Deep calleth unto deep at the noise of thy waterfalls: All thy waves and thy billows are gone over me." — Psalms 42:7 (ASV)

Deep calls unto deep at the noise of your waterspouts.—Better, Flood calls unto flood at the noise of your cataracts. The exile is describing what was before his eyes and in his ears. There can, therefore, be little doubt that, as Dean Stanley observed, this image was inspired by the windings and rapids of the Jordan, each hurrying to dash itself with still fiercer vehemence of sounding water over some opposing ledge of rocks “in cataract after cataract to the sea.” Thus, every step taken on that sorrowful journey offered an emblem of the griefs accumulating on the exile’s heart.

The word translated as 'waterspout' only occurs elsewhere in 2 Samuel 5:8, where the Authorised Version has “gutter,” but it might also be translated as “watercourse.”

All your waves and your billows.—From derivation, breakers and rollers. The poet forgets the source of his image in its intensity, and from the thought of the cataract of woes moves on to the more general one of “a sea of troubles,” the waves of which break upon him or roll over his head. The image is common in all poetry. (Compare to “And as a sea of ills urges on its waves; one falling, another, with huge (literally, third) crest, rising.”—Æschylus, Seven against Thebes, 759.)