Why does it say "Sa Kinah"?
Radak: So lamenters will lament over you.
What is the meaning of "Kefir Goyim Nidmeisa v'Atah ka'Tanim ba'Yamim"?
Rashi: You should have crouched in your river, like fish do, and not gone out to the dry land. You were haughty in your heart, and compared to yourself to a young lion, which goes out to tear prey.
Radak: Like a young lion amidst Chayos, so you were amidst Chayos. You were like the great Tanim that crouches in its rivers. The Mem at the end of ka'Tanim is in place of a Nun.
Malbim: In one aspect, Pharaoh is compared to a young lion. It does not leave its abode to tear prey. It tears only what comes close to its den. Only an Aryeh (mature lion) leaves its abode to tear prey. The nations considered [Nebuchadnetzar] like a young lion ? he did not go out to conquer distant lands and agitate the land. Even so, he harmed all his neighbor, like a Tanim. The Egyptians believed that the great Tanim (crocodile) is Kadosh and rules in the water. You lie on your belly, and your legs cloud the water in your rivers (Mile), and this tramples the rivers of the Goyim 1 . The Egyptians believed that the god that rules over the sea, it wars with the god of the Nile. You are like a Tanim that rules also in seas! Even though on the land you were compared to a young lion that does not leave its abode, in the seas you damaged greatly. He conquered all the nations by the Pras river and on the sea shore. He drew the influence to him. All of them served him and paid a tax.
Malbim: When the Tanim (crocodile) tramples the Nile river, the water of all rivers is expelled and there is a storm at the bottom of the water. The low water is raised, and it floods and passes to the Nile, which become full. The other rivers lack water, for it passes to Nachal Mitzrayim.
What is the meaning of "va'Tagach b'Naharosecha"?
Rashi: You will go outside with your rivers. This is like "Gochi mi'Baten" (Tehilim 22:10), "Ki Yagi'ach Yarden" (Iyov 40:23) ? something that flows and comes out from a hidden place.
Radak #1: You will bring water out with (via) your rivers to the settlement. The prefix Beis in b'Naharosecha is like "Becha Tzareinu Nenage'ach" (Tehilim 44:6; it means with/via).
Radak #2: You will go out with your rivers to flood the land. The rivers are a Mashal for his soldiers.
Malbim: Refer to 32:2:2:3*.
What is "va'Tidlach"?
Rashi: It is an expression of cloudiness. (Refer to 32:2:6:1.)
What is the significance of "b'Raglecha"?
Rashi: You did not have legs, and you made for yourself legs, like Chayos, to pass through the waters [Radak - of other lands] and trample the rivers. Targum Yonasan is like this ? you fought with your camps and terrified nations with your support, and destroyed lands.
What is "va'Tirpos"?
Radak: It is the same as va'Tidlach; the matter is repeated in different words. It is trampling in water and making it cloudy. If the water is not deep, his feet reach the ground and raises mud, which clouds the water. This is a Mashal ? he fought with many nations and destroyed their lands.