Who will roar, and over what?
Rashi: The enemy, over [conquering] Am Hashem, who were mentioned above (25).
What is "Nahamas Yam"?
Rashi: The sea's waves make great noise - so the enemy will come with noisy troops.
Malbim: The afflicted nation is depicted as a boat in a storm that is about to break. This metaphor is used also below (17:12) and in Tehilim (93).
What is the meaning of "v'Nibat"?
Rashi: It is an expression of looking. Yisrael will look, hoping for help from the kings on whom they relied - "ha'Yoredim Mitzrayim l'Ezrah" (31:1). Nibat is Nif'al; the prefix switches it to the future.
Radak: It is Pa'al conjugation, like Avad, Shavar. When the enemy comes, Yisrael will look for help, but they will not see, for it will be dark.
Malbim: People on the boat (refer to 5:30:2:2) strive to return to dry land, but they cannot.
What is the darkness?
Rashi: No one will help them.
Why does it say "Tzar va'Or Chashach"?
Rashi #1: Both the victim of the affliction, and the one who comes to illuminate for him, will be dark.
Rashi #2: Tzar refers to the moon; its light was diminished. Va'Or refers to the sun.
Radak: Tzar refers to the previous word "Choshech", even though the Trup (notes) imply oppositely. The darkness is due to the enemy. Also refer to 5:30:6:2.
What is the meaning of "ba'Arifeha"?
Rashi: When its darkness will come. Arifeha is an expression of Ya'arof, like "Ya'arof ka'Matar Likchi" (Devarim 32:2). When rain descends, the air darkens.
Radak #1: [The sun's light will darken for Yisrael] in Shamayim, due to their affliction. Shamayim is called Arifeha, for it makes rain drop - "Af Shamav Ya'arfu Tal", "Ya'arof ka'Matar Likchi" (Devarim 33:28, 32:2).
Radak #2: In its desolation 1 , like "Ya'arof Mizbechosam" (Hoshe'a 10:2), which is destruction.
Malbim: The cloud (refer to 5:30:5:4) pours rain on the boat. Sailors cannot save in such a case.
Presumably, the text should be 'b'Charvoseha', like Kli Paz cites Radak to say. (PF)