What is the comparison to cities that were never settled?
Radak, Malbim: When the rock [on which Tzor was built] will appear smooth, it will seem that there was never a city there.
What is "b'Ha'alos Alayich Es Tehom"?
Rashi citing Targum Yonasan: When I will raise upon you camps of nations numerous like the depth, and many nations will cover you. Radak ? he translates the verse to be a Mashal.
Rashi (based on the simple meaning): First it was given over to Nebuchadnetzar; afterwards, the sea flooded it.
Why does it add "v'Chisuch ha'Mayim ha'Rabim"?
Radak: The matter is repeated in different words. Above (5), it says "Mishtach Charamim Tihyeh." The water covered it a short time. It flooded it, and afterwards the waves went back and the rock was exposed and dried.