Psalms 98:8

Let the floods clap their hands - נהרות neharoth , properly the rivers - possibly meaning immense continents, where only large rivers are found; thus including inland people, as well as maritime stations, and those on the sea-coasts generally; as in those early times little more than the coasts of the sea were known. The Gospel shall be preached in the most secluded nations of the world.

Let the hills be joyful - All the inhabitants of rocky and mountainous countries.