Charles Ellicott Commentary Psalms 148:7

"Praise Jehovah from the earth, Ye sea-monsters, and all deeps." — Psalms 148:7 (ASV)

Earth —The invocation now passes downwards, and the first sound of terrestrial praise is to come, according to the order of Creation in Genesis 1:0, from the sea-monsters (for which see Note, Psalms 74:13; Psalms 91:13), the “deeps” being added to include all great waters in which such creatures are found.