Albert Barnes Commentary Psalms 98:8

"Let the floods clap their hands; Let the hills sing for joy together" — Psalms 98:8 (ASV)

Let the floods clap their hands - The rivers. Let them join in the universal praise. As if conscious of their beauty, their grandeur, their usefulness; as if aware that all this was conferred by God; as if rejoicing in the goodness of God manifested to them, and through them, let them unite in the universal praise. Compare with the notes on Isaiah 55:12.

Let the hills be joyful together - The mountains - in view of the goodness of God toward them - crowning them with beauty - clothing them with sublimity and grandeur - let them also rejoice in God as their God. Let all nature thus join in praise.