In this verse the prayer repeats expressions from the song of victory in Exo 15 that Moses and the Israelites sang after crossing of the Red Sea. The concise description with the climax in the form of a comparison is powerful and dramatic.
Thou didst divide the sea before them: God separated the water of the sea into two parts or sections to make a dry path where the Israelites were able to cross from one side to the other side. God caused the water to separate in two in front of them. The concept of dividing water to create a space in between may be difficult to express. It may be helpful to specify that the water of the sea was separated into two sections. Mandinka says “You split the sea before them.” “You traced a road for them in the sea” may be another way of expressing this.
They went through the midst of the sea on dry land: The prayer shows God’s power by drawing attention to an apparent contradiction. How can there be dry land in the midst of the sea? The prayer simply affirms that God caused the water to divide. This left a path of dry ground for the Israelites to walk across on to the other shore. The idea of dry earth at the bottom of the sea may seem to be impossible, which is perhaps why Jerusalem Bible says that the Israelites crossed “dry-shod.” In some languages this may be expressed with an idiom such as “with dry feet.” The Israelites crossed through the divided sea on dry soil without their feet getting wet.
Thou didst cast their pursuers into the depths: In sharp contrast to the deliverance of the Israelites, the Egyptians who were following them met with sudden disaster. The prayer does not explain exactly how the sea was divided and how the Egyptians perished, but it does give credit to God for throwing the Egyptians into deep water where they drowned (so Good News Translation).
As a stone into mighty waters: The fate of the Egyptian soldiers is compared to throwing a stone into “rushing waters” (Jerusalem Bible), “raging waters” (New Jerusalem Bible) or “turbulent waters” (New English Bible; see Exo 15.5, 10). The comparison with the stone may need to be made more explicit as Good News Translation has done by including the idea of sinking and by specifying that it is in a “raging sea.” Both the Hebrew word for waters and the adjective that is translated as mighty may refer to the water of a sea or river.
Quoted with permission from Noss, Philip A. and Thomas, Kenneth J. A Handbook on Nehemiah. (UBS Helps for Translators). New York: UBS, 2005. For this and other handbooks for translators see here .