When did Hashem cast him?
Malbim: This was when they cast him from the boat to the sea.
What river surrounded him?
Radak: The river that enters the sea. Ibn Ezra says, this was where [the sea] joins to the river.
Malbim: Flowing water is called Nahar. Yam is stagnant, collected water. However, when a storm breaks out, the water goes up and down, around in a circle; it is called Nahar.
What are "Kol Mishbarecha v'Galecha"?
Targum Yonasan: The torrential sea waves. Rashi ? they are called Mishbarecha because they are Shover (break) the sea.
Radak: When waves break vigorously, they are called Mishbarim.
What do we learn from "Alai Avaru"?
Malbim: He did not float on the waves, like the episode with R. Akiva (refer to 1:5:3:1*). Rather, he fell to the depth; the water inundated below and waves passed above over him.