Why does it say "v'Atah"?
Malbim: If they trembled so much over the Kol of your fall, all the more so the islands will fear your downfall!
What are "ha'Iyin"?
Rashi: This is like ha'Iyim (the islands). Radak ? the Nun is in place of a Mem. Also "l'Ketz ha'Yamin" (Daniel 12:13) is like ha'Yamim. Yonason translates Parvarya, and so he translated "ha'Iyim" (above, 15). However, "Nivhalu ha'Iyim Asher ba'Yam" he translated Nagvasa Di v'Yama. He translated differently because the verse repeated it. Parvarya are forest areas or villages, and so Yonason translates "Migroshos" (27:28) as Parvarya. Also Chazal discussed Parvarha 1 .
Gitin 8b mentions Parvarei Yerushalayim. (PF)
What is "mi'Tzeisech"?
Rashi: From your going out to Galus.
Radak citing Targum Yonasan: When you go out to your Galus.
Malbim: The sea will cover you. You will cease to be an island; you will be only sea.