This chapter is almost exclusively on Tyre and the destruction that will befall this city because of their involvement in the captivity and the exile of the people of God. We read in vs.7 that Babylon is going to be the force that is bringing this destruction upon Tyre, just as they were seen as an instrument of God in bringing about his destruction. Again, keep in mind that they are a secular nation, pagans who worshipped idols, and yet God was going to use them to bring about God's purposes.
Just to give you a taste for what is about to come, Tyre is going to be our focus again in chapter 27. It might be helpful to see where the modern day Tyre is today. It is in current day Lebanon. Just fascinating to see that these locations in the Bible are related to modern day locations as well. Here is a map of where current Tyre would be located.