Jeremiah 51:36 - Ellicott's Commentary On The Whole Bible

I will dry up her sea... — The nouns have been variously interpreted, some commentators referring it to the “sea” of confluent nations, and finding the wealth of Babylon in the “springs” that fed its greatness; others to the Euphrates, or to the sea-like alluvial plain, intersected by canals and streams in which the city stood, often flooded by the river, so that it became as an actual sea (Herod. i. 184), or specially to the large lake described in the Note on Jeremiah 51:32. So in Isaiah 21:1 Babylon is described as “the desert of the sea.” The Hebrew word for “springs” is in the singular, her reservoir. Probably the literal and figurative meanings run into one another, and the “drying up” describes the exhaustion of the power of which the “sea” was the symbol. In Revelation 16:12 we have apparently an allusive reference to the language of this prediction.