The floods is a term used for the primeval waters, the watery chaos, “the deep” in Gen 1.2. (Revised Standard Version translates this same word as “the deeps” in verse 8.) Here the plural is used, so “deep waters” (New International Version) or “deep sea” (Good News Translation) is better. Cover them is present tense, but others have “covered.” The tense is not indicated in the Hebrew verb form, so one must interpret the context.

They went down is the usual word for descend, but here “they sank” (Good News Translation) seems appropriate. Into the depths is another word for the deep sea, so it is possible to say “they sank to the bottom.” Like a stone is a simile that is repeated in different form in verses 10 and 16. In each case it is a discourse marker that signals the end of the “narrative” and the beginning of the “response” in each of the three parts of the song. (See Muilenburg’s pattern above.) Contemporary English Version eliminates the semantic parallelism, which would be unnatural style in modern English:

They sank to the bottom
just like stones.

Quoted with permission from Osborn, Noel D. and Hatton, Howard A. A Handbook on Exodus. (UBS Helps for Translators). New York: UBS, 1999. For this and other handbooks for translators see here .